In the 33 years I had my Street Hemi, I never had that much oil in the tubes.
Pulling the plugs, I'd see maybe 1/4" of oil up the threads, as the tube's fit to the head was of course opened up without the plug holding it tight.
Stock heads (though ported) & covers, NOS tubes & o-rings, nothing special.
(Even ran the plug sealing rings early on until I figured that out & replaced the galled tubes.)
I'd make sure the fresh plugs were tight, but nothing herculean.
Half full of oil sounds like the tubes are cracked/split...