It sure looks good and solid. More pics please.

 

looks great! same here, more pics!

 

Hey OP, as the proud owner of an M22 that was built from parts from God knows how many transmissions (syncros were gone, changed them out, seals and bearings replaced, slapped back together with the gears ever so slightly worn on the corner of the teeth) set up behind my 360cid with about 500 horses let me tell you something. The super t10 WILL die, its just a matter of time, that M22 ROCKCRUSHER won't. there are ONLY 3 things that can kill a rockcrusher. 1 you built it wrong. 2 you put more than 1200 horses in front of it and expected it to hold together. 3 70mph to naught suddenly due to impact (e.g. t-boning someone on the interstate or something) While the super t10 is a damn good transmission, the m22 is THE BEST factory 4 speed ever built. and thats just going by the numbers, zero opinion there.

 

I'd agree that nothing trumps a M22 Muncie! It is the best 4 speed trans a factory ever offered. But I disagree that it's unbreakable, and there's been enough broken to prove that. Given enough time, and the right amount of thrashing behind an engine with BBC torque and HP, it will also break. It's just going to take it a lot longer than a Super T10. The M22 was rated at 500 hp by Muncie, and if you convert them to the Italian gears, and cast iron midplate, that ups the HP rating to 600 hp. The Super T10 is rated about 125-150 hp less in an aluminum housing. It also can be changed to either the cast iron midplate, or the early 80's complete iron case, which ups the HP rating about 100 hp.
But in the OP's combination the Super T10 should last a very long time. GM put them behind many high HP applications, and many with more HP and torque than his situation. The way he drives, or uses his car will determine how long it lasts, along with the condition of the trans when installed. I put a Super T10 in my '63 Falcon 2 years ago, behind a well built .040" over 454, pushing over 500 hp. The car has seen pretty hard launches with big slicks at the drag strip, and is used a lot more on the street, with occasional playing around. It was a fresh rebuild when I put it in, and it's held up great so far. I wont go so far as to say it will never break, as that's foolish. Everything breaks sometime, but my experience has shown the Super T10 is a very durable transmission, even under hard use with a big engine.
But I'd guess since the OP posted this over a year ago, he's either still running it, or by now figured out how it has held up.