Crank end play, destroyed converter, 408 nightmare

Thanks for the answers, these are the engine specs till now:

1976 360 block 0.30 over
Scat cast steel crank
Scat I-beam rods
+5cc flattop pistons
windage tray
stock oil pan and pickup
Melling HV oil pump
summit double remote oil filter with stock oil filter plate
Rapom alu heads 2.02 intake 1.60 exhaust valves 65cc
Comp hydraulic flattapped xe274 cam
Edelbrock air-gap intake
about 10.6 to 1 compression
Hughes 2500 stall converter
TF-904 reverse full manual valve body
8 3/4 with 3.23 to 1
Car is 1974 Plymouth Scamp

wanted to install
-the new cometic head gasket (.086 thick) to bring the compression down to about 10.5
-change to the comp xe275HL cam with comp double 995-16 valve springs
-install the milodon 30940 pan with new pickup and remove the windage tray
-replace the stock oil filter plate with the canton one
-install the moly coated fuel pump extensioner
-install a timing chain tensioner