Car wont restart after sitting for 5min ???

I have no trouble with 87E10, not @1 minute,7 minutes, 20 minutes , whatever minutes. But I do after 6 days,lol.
Assuming your SBM is in good mechanical condition;
check your Transfer-slot exposure. Depending on your cam and compression, it should be square to slightly taller than wide,but NOT LESS than square........ you cannot expect the engine to start if it ain't pulling fuel from the transfers, or if it's pulling too much.
My 367 starts like a Mazda,lol, namely; click-vroom-vroom. And it doesn't care one bit about the ambient temp, once the engine is warm.
Remember;square to slightly taller than wide,but NOT LESS than square