I have that truck it has a 383 going in a 4l80e a low gears. It should be fine even on a farm. I really is a little torque monster with free breathing heads.
Found this on Alliexpress. Hope it is helpful.
Check it out! $47.48 28%OFF | NCR60E 4L60E Transmission Wire Harness Adapter Stand Alone Controller Manual Shift Conversion NCR 60E-T 1993-2008
https://a.aliexpress.com/_ms4kUfY
Also still looking for a K3500 crew prop shaft frame cross member.
I am doing a 383 also cost of the conversion is higher for LS. Not enough benefit. These are trucks you really more wanting torque. I am having mine remanufactured as a 383 for 3k. Probably a little less if I was not having it shipped back.
Besides the tire's, it is your engine set-up. Which means some work. You're cam needs to be swapped for lower rpm power. Why I know this is currently putting in a 383 stroker in with a tow came for camper duty. Why the stroker bigger piston and longer stroke equals torque. Why GM did not even do...