It is not necessarily clear to us what you may or may not be flexible on. Like John said, the DP4B is not stock, but similar in that it is a relatively low rise dual plane manifold. My experiance is, other than some Mopar guys, nobody else will know the difference and it is a nice step up from stock IMO. There are little things that you can do to add power and performance in a stock package during a rebuild. Maximize the CR for the gas that you have, get the right cam, and put on the best prepared heads you can afford. If there is a larger carb that is acceptable to you, do that too.