92 2.3 pick up compression ?

Working on a friends truck and need some help. I just replaced the head set the timing and got it running ok. went to take it for a test drive and it had no power. On the way back to the house the muffler fell off(rusted) Im thinking that the exhaust is the problem due to a clogged cat and or the lack of back pressure. The other thought is the engine compression, the truck has 350k on it.

My question is what should the compression be and what is the correct way to test it.

Thanks fir the help.