340 Cam Kits which ones work with a stock block

The 284/484 will definitely give you a choppy idle. It should be in the 240-242 range at .050. If you do buy that cam , DO NOT get one other than the 108 LSA model. In a stock 340, grab a degree wheel and install it at 100-102 ICL.

Put plenty of initial timing on it and it will be decent down low.

If you don't already have the cam, look for something other than a MP grind. There are plenty of similar grinds from other companies out there.