Cam advice for ill advised 318 combo?

If you get a set of 10.5 pistons, with the J heads on the 318 your final compression ratio will be 9.2:1. Otherwise you'll be below 8:1 with stock pistons.

a stock 340 cam or close (260 - 270) duration will work nice with a set of Rhoades variable duration lifters.

I ran a similiar combo before and got 17.75 MPG with 2.76 axle.