[Kahuna]

IMO
Make the engine as large as you can.
Balance the engine
Ross pistons with the metric ring pack are excellent
Do the mild cleaning up of the ports
Do not waste your time relieving the engine
I believe the Offy manifold has the fan mount offset. May be a a consideration.
Maybe the Edelbrock is a better option
Get a cam, maybe the L100 from Krylon. It'll work well
Raise the compression at least 8:1. More if possible
You'll have a great engine
Jim