Update:
No problem Graham, the head is good and that's the main thing. Chevy was making the Blue Flame Vatte engine in 54 so its feasible the 54 848 head was high compression also, atleast on the Vette 235's it had to be....
Finally got the new oil pump in the day before Christmas Eve. It looks new and not refurb'ed. It has USA cast into it along w/part# M29. The original has the OEM long part# cast but no USA, otherwise they match up nearly identical. Wonder if the pump is actually cast/made in the USA?
Pre-oiled and installed the pump, gave all moving parts a good squirt down w/my assembly lube concoction and closed up the bottom end. Those Best Gasket gaskets lined up perfectly.
Went on to assembling the valve train and ran into another snag.
Since I installed a 3/4 cam I also had to go w/new lifters and pushrods. I prelubed the lifters and installed them. They fit great w/no side play.
But when I started installing the pushrods I discovered 8 were about 3/4" shorter than the other 4. The boxes were new and unopened and a quick call to the supplier indicates that the manufacturer has been making similar mistakes on several of his other orders. He says they are opening them up and checking every box now. The correct longer pushrods are on their way.
Surprisingly I wasn't all that put out by this little setback. You see if I'm going to cast stones I'll have to start w/myself. When I stepped back and was looking over my work I couldn't help but notice this little plate w/2 screws just sitting there laying on the bench. Those who've rebuilt these old Stovebolts know what I saw and what I've got to do........
A few pics:
Oil pump casting oil pumps oil pump installed lifters 
