70.3 to HM, what will happen?

Maybe a short term issue, maybe a long term issue, maybe nothing.  If I were you I would get a sports massage and/or see someone verse in active release therapy to make sure there's nothing "building" in the legs.  Sit in a cool tub of water, your spent and sure there's some inflammation. If you do it let us know how you feel/felt.  I know when I did my 1st HIM the week after was typical but 10-14 days out seemed to be the worst for me.

BTW, congrats on the HIM, sweet time!

Hmm???  I did a Marathon in 2008 followed by a 5K race 6 days later.  I stated out the 5K feeling like I might actually be able to pull off a respectable time, but around the time I was finished with the 2nd mile I felt like I was in the last 6 miles of the marathon all over again.  I got passed by tons of people in the last mile and finished about 90 seconds slower that what I had been running 5K's leading up to the Marathon.

Since you ran a very fast run split in your 70.3 I assume that you also did hard efforts in the swim and bike and that you didn't leave much out on the course.  If that is the case then it will take longer to recover that if you have something still left in you when you crossed the finish line.  I personally take at least two week easy to recover following 6 hour race and possible as much as a month.  Trying to do another race in that recovery period could be a good recovery run but may not see the times that you would if you were fresh and fully recovered.

This spring I did a 70.3 and then three weeks later did a 5K.  My legs were still had some residual stiffness from the 70.3.  I had been taking it really easy (only 4 miles a week running and not much more time on the bike and even less time in the pool).  I expected that race to be more like the 5K race I did 6 days after my marathon, but it was actually the fastest 5K time that I had run on more than 6 years and I was the overall winner at the event. So set your expectations low and use the first 5-10 miles as a recovery run but if you feel good after that don't limit your performance and run at what every pace feels comfortable.    

Yes, please report back on how you do.  We learn our limits by testing them.  This will be a teat and will all will learn about physical limits from how well you do. 

Nothing like a nice easy bike ride to shake out the legs...

When I did my 1st HM I planned a 7:40 pace and ran north/south of that the whole way for a 7:39 average.  I did not have anything left at the end, I felt like I was barely moving on the long chute to the finish line but our friends watching/cheering said I was hauling it!

BTW, nice run, glad things worked out for you.  Your next race should be a lot more interesting.

You really need to run your own race.  Learning to listen to your body will get you a lot better race times then trying to calculate what split times should be for every section of the race.  Try doing what you did the last 10K of your last race.  Don't look at the watch, but go by feel with different efforts (i.e. tempo vs. racing) at different section of the race.  I break things up into the first 5K, the middle of the race, and the last 5K.  

The first 5K I stay at a comfortable pace.  No racing.  The fastest I want my first 5K to be is 2 minutes slower than my PR for the 5K.  

The middle of the race I don't have any time goals per say, but I know what 10 mile spits put me on pace for a good race and which don't.  I may look at mile splits to see what pace I am at, but don't have any cumulative times for anything between the 5K and the 10 mile mark.  I think that the middle of the race would be my "tempo" effort.  If I can find a runner that is at the pace I want to be at, I will stick with them, if not I usually working on catching one runner at a time.  I usually don't have anyone passing me at that point since I start off slow and come from behind, but if I went out too fast or am otherwise struggling I just focus on running even splits at a sustainable pace.  

I am not sure if I have ever ran the last 5K faster than the first 5K but that is not because I haven't tried. My goal in the last 5K is to me be with in 2 minutes of my open 5K PR.  I think I may get their some day if I keep at it.  At any rate I pass a whole heck of a lot more people in the last 5K than ever attempt to pass me.  This would be the "race" portion of the race.

My first half marathon I didn't look at the watch much.  I finished with 6:21 min/mile pace and felt so good that I was wishing that I had done the full marathon.  (Note: after doing some full marathons I am hapy with the 1/2 marathon distance.  I love being able to run hard and still walk down stairs the next day, still run the next day, still have toe nails, etc.).  

Yeh, that's pretty impressive

What did you do for the pacing?