Replacing T-56 six speed with an Auto?

[HTX86chevy]

Hey guys, I just bought a nice 1972 stepside. The guy I bought from did most of the work Himself. It has a LS1 from a 2001 SS Camaro with a .598 comp cam and a 6 speed T-56 tranny. Also has a rear end from a 77 town car (If I remember correctly).

Anyway, the thing is completely overpowered in my opinion and I am not a fan of Standard Transmissions. Anyway to tone it down a bit and swap the tranny to something Automatic?
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