Summit Cam Help/Recommendations

I have just about the same stock lower engine as your 360. I home ported the heads, milled .043 and use the .028 Mr Gasket for the heads.The cam is a Crane H-260-2. Crane Hydraulic Flat Tappet Camshafts 693901.
Also running Edelbrock performer intake and 1406 carb. 904 trans, 2400 Converter and 3.55 gears all in a heavy B-body. Unmeasured CR is around 8.4:1 with 155 psi cranking compression measured. The mill is no barn burner but it runs well in my all around cruiser. As suspected, it needs more CR using pistons to really wake it up just as others have pointed out here. The head and intake milling (you will have to match the intake to heads for sealing) were the most expensive part of the work at around $600 including valve cut and I have about $1200 total. I was short on funds and was my first "build". Looking back now I would have done it differently and had a stronger build. Not trying to discourage you but think about your long range plan for the car. For myself I would....

Keep the 904 rebuild going and step up on the converter. Gotta match your future RPM range/cam to that.
Closed chamber heads. The smog heads are hurting you. Swap meet, CL, or someone here may have some cheap. Iron ok.
Rear gears. Something like 3.55:1 or lower if you cruise it around town only. 8.25 rear is fine.
Cam as recommended here but you will also need springs, lifters and possibly pushrods. $$$ to do it right.
Lastly...Pistons. Would possibly need overbore and balancing. $$$$.

Another option is is to just swap in a low mileage Magnum 5.9. Might be able to score one for $500 and bolt on your LA gear.
Best to buy a running engine and do a compression test.

Hope this helps.