I have the "heat soak" issue.
I decided to upgrade to the corvette starter and picked up a reman starter. It wouldn't engage. Bypassed every relay involved, checked all wiring.
After running out of things to diagnose, I put the old starter back in and it fired right up. I chalked it up to a bad starter.

I went ahead and ordered an AC delco starter online, and went with the late L98 corvette starter while I was at it. Nippondenso 336-1054 or GM 19133850.

I installed today, and I have the same no crank issue. It doesn't even try to engage.

I'm out of ideas here.

 

Also, the car has an L05 swap. The part numbers are on my old starter, and I confirmed it is an l03 starter for a 153 tooth not a 168 tooth truck flywheel....so thats out.

 

Broke down and picked up a reman stock direct drive pig starter. Put it in, works fine. Still wish I could have figured the other out.