340camshaft with stock conveter?

well according to carb book I am on ported vacuum, did it with vacuum can disconnected too.... I added a timing tape to a replacement balancer, and was reading around 18-20 idling in park, would need to get another person to help with the in gear thing, I believe it is vacuum leak maybe with the booster, everything new except the brake booster, and master cylinder, when brakes applied 3/4 to full apply to hold rear tires still in gear is when idle drops down to near nothing and dies. pop up into neutral or park ok. , will chase down for a leak later, car is too loud to hear it... will sue the old school methods. as for advance, stock electronic distributor with the large loop spring removed and a lighter one replaced for better advance curve, the other regular standard spring still intact. according to what i read this was how to just go up from a stock design curve....????