Major engine problems

[BADAZ chevy guy]

I found a 80-85 350 truck engine in the wrecking yard last month. It HAD good compression all around 160-165 on all 8 cylinders. I installed a Summit Racing SUM-1102 camshaft kit and did a 30 minute break in @1800 to 2200 RPM. Intake manifold is an Edelbrock 2101 with a stock Quadrajet from a 1984 to match up with a 700R4.

From the first test drive the engine has no real power from a standing start and just moderate power above 20 MPH. Then loses all the power at anything close to top end.

Then yesterday I busted a heater hose and overheated the engine quite badly. Now I'm doing a new compression test and I'm getting 115-120 on all 8 cylinders.

Questions:
1. What would cause the initial low power? (Checked the cam gear timing marks, Distributor is NEW and dropped in the right spot, Carb is a Reman from Carb from National in Florida and worked fine on the old engine. Lots of power.
2. Why did I drop compression on all 8? I could understand 2 cylinders lost because of a head gasket or cracked head, but ALL 8? Tested with two different gauges.

Any thought? ANYONE!!!