water pump locked up threw belt,bent all valves. install used low mileage head , after having checked for crack,plained surface, vaccumed test each valve,didn't have valves ground.which were good from vac test. aligned cams with tool on rear of head. doing compression test and #2 cylinder is 35 psi lower than others cyl. that are running 175 psi. added some oil to cyl. to do comp test not much changed. checked cam to lifter gap with lob pointing up and with in specs. have not put plugs in and tried to start engine. ANY SUGGESTIONS?

 

It is possible that the piston rings on cylinder 2 were not up to the same compression ratings as the others prior to your water pump failure.
If so, even with the new head the compression on that cylinder may remain lower.
Leave it a while and see if there is an improvement over a period of time.