Slant Six Distributor Won't Budge!

After all the years of not moving, the O-ring is stuck. Clean around the block as best you can.Leave the clamp loose and apply a good spray of penatrant and let sit over night if you can.Give it a few lite taps(hard to do on a slant) the next day and it should move.Kinda tight with the oil filter,fuel lines,cap wires etc all on that side.