I am trying to gauge how much running factory exhaust manifolds is going to hold my 360 back.

Tomorrow i'll kick off making the following modifications to a 1976 2bbl 360:

Comp Hyd Cam [last line shown below]
Edelbrock Performer RPM intake
2.02 J-Heads - milled, 63cc chambers
650cfm Thunder AVS carb


This setup on with long tube headers on my 323 [318 +0.030"] made about 270whp with a 904.

I am thinking the bigger bore 360 will help with potential valve shrouding, perhaps have a decent ~9:1 compression ratio but it will be running through factory exhaust manifolds.

Any estimate for what I may be able to get out of this 360/727?