427 s/o engine melt down??????

[HSSS427]

I think I toasted my brand new engine!!! Say it ain't so, but here are the details thus far.......

Rebuilt 427 s/o by Keith Craft - approximately 300 miles since install. Went for a spirited ride on Sat and while coming back down the highway I did a rapid acceleration and suddenly felt hot humid air coming through the footbox vent. I shut down the car and coasted up the next exit. Water temp was about 90 c and oil temp hadn' really shot up. Found that I'd thrown the fan belt, and the overheat had blown the lower radiator hose connection off the water pump and sprayed the water all over the engine compartment. Replaced the fan belt, filled with coolant, and made it back home to fix everything up. Just some clean-up, no problems.....

Today, went out for a short, but again spirited drive. After about a 10 minute run with the car going to high revs on short bursts (6000 rpm for 10 seconds maybe), I looked down and saw the water temp at 120 c. Shut down the engine, coasted to a stop, and found the following:
- Fan belt gone again
- Oil had sprayed out the rear goose neck breather and was running down the sides of the breather

I replaced the fan belt ( had a spare in the trunk now ). Starter wouldn't turn the engine over. Coasted the car down the hill to jump it off in second gear. When I popped the clutch, the rear tires locked up, so I went back in with the clutch, tried one more time, and same result. Let the car sit on the side of the road till it cooled down. Tried the starter again, but it wouldn't turn the engine over - starter worked, but at this point appeared the engine had siezed.

So, tow truck ride back home and it's on the lift. Haven't tried anything else, but last gauge readings I recall were 120 c on water, and oil still in 80 - 90 c range.

So, where do I start? Did I melt down the rings?, bearings? Oil temp gauge is in the pan, so is it giving false readings? What caused the oil to blow out the rear breather?

Thanks!
Scott