what cam to get

Roller or no?

if by 5.0 you mean a late model HO roller engine, just keep the stock cam. Its a good all around cam that makes good power and torque. The stock heads can't use much cam anyway. More info would be helpful-what trans, rear gear ratio, driving style, etc. If its an older hyd. flat tappet, you have plenty of room for improvement as the stock cams only have about .380 lift and around 180 duration at .050. Since you plan to use the stock heads, a dual pattern cam would help out with exhaust flow.