340 Build
Interesting combo with the trans and a great car. I passed one up some years back; that woulda been cool but no time to build it.
I would relook at the cam IMHO, and look to get something a bit torquier, not for the torque per se, but to widen the torque curve as much as possible for the road courses. And 1.6 ratio rockers would help that with a better lift vs duration ratio.
Any chance of going with lighter pistons to take out some of the mass? It'll help it to rev a bit faster, and that will show up readily in that light car. Plus take some stress off of the crank, which I would consider important the way this thing is likely going to be revved a lot. You would get a bit more weight off of the rods with I beams and be just fine for strength, IMHO. With the lighter rods and/or pistons, the re-balance would be a simple matter of computing the new bobweight, and handing it off to a shop; the crank would have weight taken off, none added, so will be a cheap re-balance.
The Air Gap might be the right intake for this because of the tight underhood space. The concern is for keeping the air cool and dense. A fresh air intake setup seems important for road courses.