If the valves are not too tight you can check the valve timing while the valve cover is removed.
These engines will occasionally strip some teeth from the timing gear and let the cam get out of time and will result in a low or no compression situation.
Easy enough to check with the valve cover off.
1) plugs out for easy engine turning by hand
2) valves on #1 cyl should be near proper clearance
3) align the timing marks to top center
4) if both valves on #1 are closed rotate the crankshaft 1
revolution at which time when the timing marks align the
valves should be open equal amounts (the exhaust is nearly
closed and the inlet is just barely off its seat and
opening)
At this time if the crankshaft is turned BACK AND FORTH
15 degrees or so the equal opening at top center will be
very noticable IF the cam is still in correct time.
Good luck
