Hard to test the capabilities of the hydraulic element. The ones that are easy have probably drained the oil from them. We always collapse the lifters in a vise to remove the oil otherwise the lifters extend and the valves don't close for a while.
I would replace any you suspect and put it together. If its noisey its easy enough to fix later. BTW if you are cutting the seats and valves (the ones not bent) you should verify the compression of the hydraulic element in the installed extended position. Another reason to get the lifters free of oil; so that they easily collapse to their proper extention/compression. They usually pop out alright but often don't collapse after being extended (only under the load of the valve springs)