8.1 vortec in a 1994 chevy dually

[Lvnspeed]

I have a 1994 dually with a TBI 454. The motor is a mess I meas a MESS. I was wondering if I could do a 8.1 in the truck. I know motor install wont be an issue I already have a 4L80e. The problem I see if the wiring harnesses. How do I adapt the 8.1 to work in my truck? will it shift my tranny? Any Advice will be appreciated. Oh yea I did a search still came up empty