Double check my engine builder please 340 stroke

I took my 340 to my engine builder for my 1967 Barracuda. I wanted the stock setup for the street driver only. I found a block for $200 I was going to redo the 340 with a 1968 318 forged crank and rods but the builder showed me that the 4” stroke would be equily economical to buy vs reworking all the original parts. I went with the 4” new components.

Here is the build details:
340 block 40 over with one sleeve
Edelbrock Alum heads 63cc pn#60779
Airgap intake
4” Scat crank pn#9-340-4000-6123
Icon forged flat top pistons IC744 (+5cc)
Hydralic flat tappits lifters
Scat 6123 connecting rods (new)
273 adjustable rocker arms (reused)
Custom Cam of New Albany MS
[email protected]. 230. 238
Lobe lift. .323. .325
Valve lift .491. 1.52x. .494
Lobe separation 113 degree in cl 108
IN [email protected]. 7BTC CL. 42 ABC
EX 57BBT. 1 ATC
340 exht manifolds w/ 2 1/4” duals
904 auto trans
323 8-3/4 rear end

They tell me the cam shaft will bleed down cylinder pressure down to 8.9 to 9.3 to use pump Gas. I looked at the JEGs tool and it says 11:1. I have questions that I’d like a second opinion

1) Is there a way to calculate the compression ratio with my custom cam?
2) They said 87 octain would be fine. Do you agree?
3) Builder recommended 750cfm carb. I like Edelbrock’s AVS carb...is he 650cfm too small or 800cfm to large for a street driver?

Thanks in advance for the advise.