Don't know the thread size. If you are losing 1psi per hour that's probably the source. Water looks rusty did you flush the cooling system entirely? I usually flush it with water through the petcock on the block from the radiator. I keep flushing until it runs clear. Close the petcock add...
No expierience, but I've seen a socket used for install with a hammer, or you could remove entire rocker assembly in 1 piece I believe. Glad it's that and not a head gasket or cracked block π.
Did you drain the pan?? Pull the inspection cover, do a visual to see if all freeze plugs are in place!! Thenrun water through to see if any are leaking π€π§π
If it was cooler I think it would've split and spill on floor but might be wrong. By pass cooler is good idea. Is the cool going into pan real fast??? If it was I would say 1 or more of the freeze plugs behind pushrod inspection plate. There are 4 freeze plugs on each side of block and 2 in rear...
Seamed down the middle (1/2"??) Panel butts up to front floor pan. Goes under flange in rear and enough material left on pan to do the rise were rear seat sits.
THEY DO EXIST π³π―π€ππ. If you ask the right person π. @remy1974 might do something for you. Overlapping really isnt the best way! All of that should be replace for longevity. Piecing would be a turnoff for a lot of buyers ππ.