A Hypothetical Distance Indicator for 70.3

Work your weakness if you plan on doing a 70.3.  If the bike course will be hilly consider that in your training and equipment (gearing).  I went from Sprint to HIM over 9 months doing my best to follow a BT HIM plan.  I lost a month near the end with a bike crash injury then a nasty respiratory infection, still did the HIM and enjoyed it.

I would say you are ready to begin preparing for a HIM.

Now you need to build your fitness from where you are.  I don't think targeting a workout 'max distance' is a great way to prepare for the race.  That said, I would guess that prior to a HIM you'd want to be confident that you could relatively easily complete a 4k swim, a 100mi bike and a 16-18mi run.  Not that any of those have to be an actual workout that you do to prepare for the race (and certainly not on a weekly basis).  But if you have relative confidence in completing each of those individually, then you will likely be in a position where you should be confident that you can complete the HIM.

why would you want to do the bare minimum and have the worst possible race performance you could have all while pushing yourself to your limits?  put in a little more time and base before the race and it will be a lot more enjoyable....  below is what I would recommend as sufficient training to not suffer and still be able to enjoy your "race experience" 

swim: 9000 yards per week
bike: 120 miles per week
run: 30 miles per week

do this and you will be ready for any course you sign up for. 

EDIT: it looks like you are asking for maximums, so here they are:

swim: 3000 yards
bike: 60 miles, it's all about the bike
run: 13.1, i'd at least do it once 2 weeks out from your race

Jason described it well above.  On race day, you will likely be exercising for 5-6+ hours.  Under your 2/3 rule, you might want to be comfortable going for 3-4+.  So, if you can comfortably swim for 30min, ride for 3hr and then run for 30min--in the same workout--then you will probably be in good shape to extend the distance you need on race day.  Again, it's not absolutely necessary for you to actually do that workout.  And you MIGHT be able to get by with the targets you have there.  But probably only if they are supported by a lot of other workouts.  For example, a long run of 10 might be enough if you are running 30+mpw and a 2k swim might suffice if you do it 3-4x/wk and a 45mi ride might be OK if you do it well above race pace and/or do it at least a couple times a week. 

If you don't have the natural talent then it doesn't matter how much training you do as a 70.3 WC spot is an impossibility.  I'd say 80% of the people that sign up for a 70.3 will never, ever be able to qualify no matter how hard they work.  The 20% that do have a chance can do so based on some combination of talent and hard work.  

It's been mentioned already but one workout or distance indicator doesn't really mean much.

I've done 1:05 IM swims on never having swum more than 2500m in training.  Sub-5 IM bike split (actually 5:0X but had a mechanical issue that cost me several minutes) with no training rides over 85 miles, then ran a smidge over a 4:00 IM marathon having not ran more than 12 miles in training.  I probably would've gone a wee bit faster had I done some "longer" stuff but it was my overall volume and consistency that really mattered.  I was swimming 10,000 meters per week, cycling 8-9 hours, and running 40+ miles per week.  I just didn't do much "long" stuff.

Originally posted by Snaaijer  I think one of the only reasons to approach race distance is to keep your mind at ease, but once you've figured out that you can perform similarly (or even better) on consistency, that argument has no merit anymore

For some reason it's very, very hard for people to grasp that very simple concept.

Not saying that going long in training is a bad thing.  It has its place.  People tend to: a) place way too much emphasis on the weekly long workouts (IMO, the long run and long bike are the two most overrated workouts in triathlon), and b) do too many long workouts which can affect recovery (both mental and physical) and future workouts.  I see way too many "I'm going to do six hour training rides every week for 10 weeks" and "I'm going to do 20 mile runs every week" kind of nonsense.  It just isn't necessary.

Originally posted by GMAN 19030

Originally posted by Snaaijer  I think one of the only reasons to approach race distance is to keep your mind at ease, but once you've figured out that you can perform similarly (or even better) on consistency, that argument has no merit anymore

For some reason it's very, very hard for people to grasp that very simple concept.

Not saying that going long in training is a bad thing.  It has its place.  People tend to: a) place way too much emphasis on the weekly long workouts (IMO, the long run and long bike are the two most overrated workouts in triathlon), and b) do too many long workouts which can affect recovery (both mental and physical) and future workouts.  I see way too many "I'm going to do six hour training rides every week for 10 weeks" and "I'm going to do 20 mile runs every week" kind of nonsense.  It just isn't necessary.

I agree.  I also think people get caught up too much with strictly distance or time and somewhat dismiss the role of intensity.  They rather go longer and easier than shorter and harder.  Even though it's very much possible to generate more training stress with a shorter and harder workout, while allowing more time for recovery since you're workout is done sooner.