318 build
Welcome to FABO. The kb399 pistons might be a bit high in compression with the 702 cam. The kb 167 pistons will increase your compression a bit and work better with that cam. As far as the heads a good valve job and some bowl porting is all that's needed. Bigger valves never hurt.
I’d take a second guess into actual fact of the matter since his “360” heads and what ever gasket he is making use of is an unknown.
W. See a little facts here as in how many cc’s the head has and what gasket is will be used. Then take a look here;
KB Hyper Piston - Chry 318 Rod 6.123 Solid Dome -6cc 2V [KB399] - $444.93 : United Engine & Machine Co. Incorporated, Performance Pistons
From the link above, these are estimated ratios dependent on a few variables?
Trying to follow the numbers...
60cc-11.7, +4cc’s lower the ratio .7 to;
64cc-11.0, +4cc’s lowers the ratio .6 to;
68cc-10.4, +4cc’s to 72cc’s,lowers the ratio .6 or .7, IDK, this is a best guess from following the link numbers. But the math looks like;
10.4 - .6 = 9.8-1.
10.4 - .7 = 9.7-1
The missing variable, head gasket thickness. However, you can vary this to an easy 1/2 point or more in ratio. Down to 9.2-1?
Sit down and play with a ratio calculator and various head gasket thickness and then cal Cometic gaskets for there MLS gaskets. I had a set
Made up @ .100 thick.