Not sure but the same thing happened to me a few summers ago after letting the car idle for 10-15 mins after some spirited driving...it was fine before and after any time I really hit it hard it would bog and almost die..kinda like hitting the rev limiter in a modern car

The boys here told me it was vapor lock, it never happened again after I put in a phenolic carb spacer to isolate the carb..

Hope this helps..

PLAZ