Sun Electric Co. had a slogan that they put on every piece of test equipment they built- - - - -"We Test, Not Guess!" Instead of shotgunning parts at the problem, how about trying to figure out what's going on by concentrating on making sure every system is functioning properly and is adjusted correctly? Bogging or backfiring on quick acceleration is frequently caused by either late ignition timing or an improper advance curve in the distributor. Have you plotted the advance curve on that "new" HEI? If it's one of the offshore clones of the GM distributor, there's no telling what the internal calibration is going to be. I buy those things, but I immediately scrap all the internal electronics and wiring and replace it with OEM-quality components. Then I use a delay-flash timing light to plot the advance curve, and adjust it as necessary.
Simply rolling a wheelbarrow full of new parts up to the car and swapping everything in sight would get a guy working for me fired before lunch on his first day on the job!
Jerry
