Agree: check timing belt. Even if one forgot to install any rings at all, should get some compression just from the pistons if the valves were closing at the right moment.
Are the valves adjust correctly? If they are too tight, valves will not seat, ergo no compression. Timing light not necessary for this. Crankshaft lined up on mark, camshaft lined up on mark, timed. Next set the distributor timing.
Ok everyone since I had trouble with engine I managed to find a 90 b2000 long bed LX at a pick and pull in port Allen Louisiana...... I snagged the head of it and anything hard to find parts. As I loosened the headbolts I could hear air escaping.. Today I cleaned the head real good, with a tooth brush & oven cleaner and I'm gone to resurface it and valve seals.glad to have mechanical lifters tell me what all needed. I'd just gone swap the whole head instead.