engine compression on 1998 GMC 1500 Pickup

I had to change the timing chain since it skipped and was stretched. the spark plugs, wires, solenoid, distributor, rotor, cap, fuel injectors, fuel filter, intake gasket, valve cover gaskets, water pump and now it still reads code PO300 multiple misfire. I did the compression test and there isn't any compression in cylinders 2 and 5. The other cylinders are low on compression as well. what else can i do? do i need to have it rebuilt or replaced. what kind of price range would i be looking at for this type of repairs?

Asked by for the 1998 GMC 1500 Pickup
do a wet compression test, to see if the problem is in the head or rings. If the compression values rise after you ad oil to the cylinders the problem is in the rings and needs to be rebuilt. if it don't change the problem is in the heads, valves or head gaskets. you would need to do a leak down test to pin point the prblem. Try this first and lets hear your results
How do you do the wet test? I haven't done one before. I am not sure what to do.
apply a small amount of oil into the cylinder to seal the rings and re do the compression test.