Though frying the HEI module probably isn't the OP's problem (not that I'd ignore the possibility of a rash of cheap Chinese unit failures!), I figured I'd mention this super little heatsink by Designed 2 Drive (Nathan is a super guy who'll take his time to share knowledge and answer any of the silly questions one might have - props to him!) that places the ugly little HEI box under a Mopar distributor:
Not only is this thing very nice and inexpensive (and comes with the small terminal for the HEI module, saving me a junkyard run), it's the perfect way to hide the GM module - especially on a pre-'73 points car, where the ignition module may be out of place or a pain to find a spot for. It doubles as a heatsink, so other than digging up some thermal paste, so it's pretty much an all-in-one problem solver.
You can hardly see it when installed:
-Kurt