As Michael C Henry noted, the block isn't the failure point, the filter is. 427 side oilers came from the factory with 125 psi. Not everyone agrees high pressure is needed; I believe it's a help to get the
oil out to the rods on top oiler blocks. The pressure itself doesn't do anything except push the
oil to where it's needed. If you want to run that high pressure, the Fram HP 1 filter is a direct replacement for an FL 1a; it has a higher burst housing and the neoprene seal is considerably deeper so it won't blow out. Sadly, to my knowledge the HP 1 doesn't filter any better than the standard Fram unit.
Dan