Loss of power with new cam
Just to throw in my $0.02, valves should be adjusted with the engine at operating temperature. Adjusting them cold to get it started is a first step, but when it warms up, pop the VC and run the feeler gauges again.
I used that cam in my '70 Duster and absolutely loved it! It certainly has potential.
Using the factory harmonic balancer to set timing can sometimes cause issues. There is a rubber isolator ring that separates the inner from the outer portions of the dampener. If the outer ring slips, timing is off. Using a positive stop in the spark plug hole, you can find TDC and mark it on the balancer. Turn the engine until #1 piston hits the stop, mark the balancer at the 0 mark. Spin the engine the other way until the piston hits again and mark 0 again. TDC will be right in the middle of those 2 marks.
Mike