Was thinking something like replacing an axle boot on a front wheel drive
car with those split and bolted types...

It would be helpful to know the type of engine, some engines (Cont) have
the pushrod tube swedged into the head.

I think Real Gasket makes a kit to replace the Continental pushrod tubes
with removable tubes. If you do pull a small Continental cylinder to replace
the pushrod seal then there's that AD to dye check the rocker arm bosses for
cracks--------

Cheers:

Paul
N1431A
KPLU