another M-1 vs Airgap question

I'd put a 750 DP on it and toss the vacuum stuff to the curb.

My friend had a 360 built similar with a slightly smaller cam, iron heads with a 2500 convertor and 2.76 gear. It got 20 mpg on the highway and about 15 around town.

With that gear and convertor, the engine will eat up every bit of a 750DP you can give it.