High Compression 390

Just everyone keep in mind that the OP is going to be at 5000' elevation MINIMUM. 9.6:1 is LOW SCR at those altitudes, because the low pressure makes EFFECTIVE DCR even lower. His atmospheric pressure is going to be almost 8"lower than standard at 7000'.

Think of altitude as 'negative turbocharging'.... when you turbocharge, you lower SCR. So with 'negative turbocharging', you raise SCR. A lot of what gets learned for typical use goes out the window at theses altitudes.

9.6 SCR with a 58 degree ICA (a smallish cam) gives you an effective DCR of 6.7 at 7000'.....that is less than most stock 318's. Cranking pressure is 130 psi with that combo... again, stock 318 territory.

The 11:1 is an actual combination with certain SCAT stoker/piston package and Edelbrock heads. So no assumptions on that matter...