Should I adjust trans

Hey All,
When taking off fast, when the trans shifts into 2nd gear, the engine RPMs increase but that car doesn't seem to accelerate that much. Feels like the trans is slipping.
I'm thinking of adjusting the trans and the youtube videos make it look easy. Should i try it? Of course, I'd be under the car doing this work.

Car is a 68 Fury with 383 and 727 trans, as far as I know they both are original. Bought the car in March and completely drained the trans and torque converter. Right...

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