will this run on pump gas ?

Nope. My limits for pump swill and an iron head with quench is a dynamic of 8.5:1. Dynamic will go up as the efficiency goes up with rpm. So you need a little room to account for that or you'll find yourself with detonation issues. I'd have the chambers enlarged by 2-3ccs when they are put together, and look at cams that have another 10 degrees on the intake and exh sides. Another though would be to go with a dished forged piston which allows for the use of a decent quench and lowers the static and dynamic.
The KBs were developed before the rise of the closed chamber heads. So they really are best for an open chamber head. With the costs of RHS, it might be similar or less to have a set of LA heads done well and forget using quench because they'll make similar power ( a little less overall but you're not looking for huge HP numbers) and you can run pump fuel with them. Using LA heads at 70ccs and the 107s gives you 9.9:1 static and 8.4:1 with that Crower cam. It's still a little high but you can always just run a slightly thicker gasket.