what places that sell electronic distrbutor cap for these engine(400) and also where can l find 750 cfm 4 bbl carb...autzone? napa?...engine is set up wit an 2 bbl now so in order for me to put an 750 cfm in it now what type of stuff do l need to get ?....also what the best flowmaster brand to add wit that 400

First of all, Pontiac made the Bonneville, but nevertheless, without extensive engine work, it will never work with 750 Cfm carb, u will need to rebuild the engine including a performance cam, get some new heads that will increase the compression ratio, different pistons etc. Lots of money. That engine with stock configuration might be able to handle a 500 Cfm, but l believe that might also be pushing it. Be careful to not over carb it. There r many sites that will allow u to calculate air flow needed. Look into them. As far as electronics look at Jeg is catalogue or other parts suppliers. Good Luck

Are u saying u have a points type distributor & want to change to HEI? Either way, the caps should be available in almost any auto parts store.

If u want to swap for a 4 barrel carb, u will need to change the intake as well. You should be able to find on in a scrap yard, but the aftermarket sells them as well. Check Edelbrock for instance.

The same places can help u with the exhaust. Flowmaster is as good as any, but l happen to like the sound of Borla.