Crank end play, destroyed converter, 408 nightmare

how many miles on this engine build? that's a lot of metal debris in the pan. I'm not totally sure, but looks like the crank thrust cheek is beginning to turn color like it may have been heating up. Is there an interference between edges of bearings and crank fillets/ no fillets.
Were you doing a lot of holding the engine at high revs and holding it against the brakes?
a brand new trans slipping on 2 to 3 shift is not very encouraging, unless you just had poorly adjusted kick down linkage.