Decode my B&M plz.

Hello
Was wondering if anyone could decode this slant pan Olds B&M?
I recently picked this up for a 394 i plan on dumpin in my 58 Olds.
R54, H2, UC1241.
The R54 Prt is easy= 54 Olds.
The UC may mean Unblowen competition,or chev?
It did have the smaller chev coupling and chev housing on it.
The stock Olds 54 housing and fluid coupling went on easy.
The full vanes inside each looked the same i was told and were not brazed.
They are crimped and tight.
Is it ok to swap the couplings like this?
What is the appox stall for launch with a stock 54 coupling?
The 394 crank bolts on no problems!
Guessin i gotta build/balance bottom end first before i give the torus cover/flywheel to the trans builder.
Can we say low 13s high 12s in a heavy car!
TIA

 

i think you're right about the "U"nblown "C"ompetition code,but i don't know for sure.
if it is expect to eat u-joints

 

you might have to grind on the block a little to clear the ring gear.
make sure to take the flywheel/torus cover with you to the balancer.
there are 2 ways to have it balanced,either removing metal from the flywheel,or welding on bnalance weights.
weld on weights is the recommended method,but make sure the mating surfaces of the torus cover/flywheel haven't warped from the heat.

 

You might want to PM the author of this thread:
http://www.jalopyjournal.com/forum/showthread.php?t=73297
He may be able to help you with some of your questions.