Well I've got my 5.7 Hemi Now what

Still has 4 wheel 10" drums. Stops on a $1.10 and I am looking forward to a front disk brake conversion. I will still keep with the manual brakes though. I don't have enough manifold vaccume for power.8)
Is the vacuum problem due to cam choice? I'm planning on a similar set-up and have the power booster and now wonder if it will work!