yes a supercharged r/t will take a stock srt8.... but whos gonna keep their srt8 stock, not me lol . the 6.1 l has way more potential then the r/t so good luck finding a stock srt8... unless its a collector who wants to keep everything original... and if that was the case he wouldnt want to put that original engine under strain racing a r/t.
as for the 392 you wont just take it with a supercharger.... the 392 crate puts out mid 500s on hp and tq..... the 5.7 SC wont reach the 392s peak.

good luck though