Old hot rod tricks for inline flatheads you say!!!! split the intake manifold, add a 2 barrel for each half (front 4 and back 4 cylinders)
Modify the cast intake manifold by brazing it---split the exhaust manifold to run a set of duel exhaust---sounds really neat-----mill the head .030 to raise the compression ratio. Those are real tricks for net horsepower gains---I have done them all in my misspent youth. When you are all finished, you will still have an old engine, and if it ever breaks you will have a boat anchor, because you will never get replacement parts.