I had a 284°/.484" Mopar cam in the 383 that was in the ex-PoPo Dippy, engine needed a minute or two when it was chilly out before the vacuum was enough to go full assist, that cam is ~240°@.050. The 'teener will probably be the same around the 230°'s with a similar profile cam. Good manual brakes are the best, My choice for an A-body of Mine every time, no worries there.