Ok, I couldnt listen to your engine for some reason but I have to say I had a '83 Chevy 305 and I am not a fan, the things had smogger heads on them and pinged just by looking at them, you might check and make sure that it doesnt have that anti knock distributor from the 80's left in it, it had a sensor in a freeze plug hole and retarded and advanced the timing automatically, well it did until I yanked it out, ran better and cut out the terrible noise. Might not be your issue but dont expect much out of the 305's. Good luck and dont forget the computers where just coming into play with these motors and it wasnt always good. Matt