Hi
you forgot to say if its a 4 6 or V8 or "family" !.............pic would be nice too!..........duzn madda!
Make sure Ignition Timing is correct. Make sure spark plugs havent failed; swap with ones in good cyl or fit new ones........ With Rocker Cover/s off, make sure ALL valves are "dancing" when you hit starter. If valves near rear of motor arent moving at all, Cam may be broken in half.
If you find 2 cyls that are zero are next to one another, it may be just the headgasket bridge between the 2, or much worse; cracked block between the 2 cyls.........re your compression spec Q : whichever cyl has the highest comp pressure (Rule of Thumb till you find the factory Specs........must be at least 150 lbs/sq inch, then they should ALL be the same +or- 5 psi.)
Either way, a tablespoon of oil in the offending cylinder/s will point towards burnt valves when you do a comp test with no improvement after adding oil.
Keep me informed how ya go