My 99 silverado 5.3L wont start or run

Just to make sure as I check timing...I should have compression building on #1 cylinder as the timing mark align, right?

Would compression be low on all cylinders if the lifters weren't pressed up? If the camshaft was broke wouldn't I have different compression pressures on each of the cylinders? Some with none, some with some...

Thank you so much for the help...I changed to different compression gage, believing that mine may be wrong. The pressure was higher (80psi) the new gage is even older but has way higher reading. I put oil in the cylinder as well, and there was no pressure difference. When I rotate the engine by hand, I begin Building pressure at about 180 degrees, on the camshaft, before the timing marks align. This doesn't seem right to me but maybe it is. When I pass trough where the marks align Ive well passed compression and power (where I'm drawing a little vacuum).

Yes I am, because it's seems my timing marks are aligned with the #1 cylinder at the top of the exhaust stroke. Perhaps for my engine 99 silverado 5.3 liter that is correct...but I don't know. Regardless the timing marks are aligned correctly, Camshaft timing mark at 6 o'clock and crankshaft mark at 12 o'clock so that the marks point at eachother. Thank you for your help, I'm walking away for a while because my head is spinning :)

Just rebuilt my 5.3 ls engine Fired on the first try shut off it will not crank back checked everything on it getting 12 V to every sensor and bullshit like that

Any idea why