[blykins]

If you want to follow Jim's advice, then you would want to set the initial at 10°, use a red bushing, and try 2 silver springs.

I don't see why that engine would need 38° total timing. The intake manifold doesn't play a part in the amount of total timing...just the compression ratio, the combustion chamber efficiency, and how the quench is set up. That engine shouldn't need any more than 34-36 total.