if you can find a bigger hole in the manifold you could try it, but i doubt it would help. Test the check valve and line(s) before anything, but if the cam is too big, and only slightly so, for the power assist to work right, I think you can get a reserve canister which will hold a little extra 'shot' for you. there are also vacuum pumps sold for this problem in extreme situations.

check jegs and summit.

edit:
check summit part
CRN-99590-1
by Crane Cams.
you could probably make one, but this one sells about $50.