I'm not a betting man, but it's likey that the piston rings are shot. It is possible that the valve seals are shot on your VTEC head, but that wouldn't explain the lagging power with the non-VTEC head.

If the compression is low on a given cylinder (>150), squirt a fine mist of oil into the combustion chamber and re-test that cylinder. If the numbers improve, then you've got your answer.

As you rebuild, take the time to fit the GSR oil pump and block girdle. If you've got the budget, you might as well upgrade to forged pistons and rods. At the very least, upgrade the rod bolts on the stock con-rods.