Stuck valve spring retainers/keeper....hellllp

TDC on compression stroke, compressed air in the cylinder. SPARK PLUGS IN the OTHER HOLES so the engine does not rotate from the compressed air. I take a hardened socket the same size as the retainer and whack it with a hammer so it pops the valve open and closed. Then I use a LEVER type compressor that pushes down on the retainer and I pick out the locks. PLUG THE OIL RETURN HOLES IN THE HEADS. You will probably drop at least one lock.