best compression ratio street build?

For what you describe, I wouldn't go to a 10-1 ratio so fast. A 9.0-1 - 9.5-1 max would be much more suiteable. If you want to run regular gas with the stock heads, a replacement 8.0-1 is what your after and from there, a slight adustment can be made on the heads for a higher ratio.

Confused? Let me suggest a combo for 8-1 -9.5-1 ratio. You'll just need a slug to get this ratio area with the head you have. KB probably has a slug for you and a calc to get a good idea of what the ratio will be with said slug.

From a grond level start, as if you have a 4bbl. allready, the OE iron intake and crb are good to go. A step up for the 360 would be a RPM or a Stealth and what ever carb you like in around 650 - 700 cfm.

Use the heads with the stock valves and a good angle valve job, just cleaned up and set up right. Use of headers are an option. And helpful in power.

With this OE looking package, I would use the Comp 265DEH (Without headers)
The Comp XE262H with headers.

these should be close to 300 HP and get very good mileage. 18-ish plus, maybe.

Going up the scale on performance parts, I would be looking at the intake and carb. (As money allows) and a cam choice would be ethier;

Comps XE268H or the OE 340 cam or the upgraded replacement which has a tighter centerline for a chop to the idle.

These will be over 300 HP and get decent mileage. 16 - 17-ish

The key's to mileage are mello cam timing, excellent breathing ablities and a great ignition. My last 318 had a similar cam to the XE262H, only from Crane Cams and the above basic add on parts, 600 Carb, intake and headers) in a less than 8.0-1 rato with a 904/3.21 gears and stock tire.

The car went low 15's with 18 miles to the gallon on a stock sized tire. More compresion and a larger valve would have been nice to get me into the mid 14's while retaining the mileage I believe.
Your 360 should do the same, only quicker considering it is a rebuilt engine and has more compresion to effectivly use the cam(s) above without a big comsumption of gas over the 318.