I'm building a 396" stroker

Yeah a 390" cid would be a stock bore 340 mine is .040" overbore or 396". .030" would make a 394" if I'm right on my math. I guess a 392" would be .020 correct me if I'm wrong here. My x-heads are 66 cc chambers they have all been equalized, but still nothing as small a chamber like on a W-2 style of head though. So I'm hoping pump gas want be a problem, if it is I can put a shorter duration cam in it and be ok.