Square body with 4l60E - Speed and Range Switch

[D13]

It's been a while but I'm still here with more annoying questions!

Project - 198x K2500, Straight 6 250, NP241 from 89 K5.
Trans - 1993/94 4L60E.

Essentially pulling entire wiring harness out of a 1994 K10 4.3 V6 to convert my old straight six to TBI, and get an ECM that will run the 4L60E. Question I have is with the shifting. ECM needs speed signal and range switch to manage the gears correctly. The 94 has those, but I think the 89 NP241 does not have the exact same set up for range switch, and it's a cable speedo. And I can't swap the cases directly (wrong side drop). Anyone got a great idea? I like my cable drive speedo but it's not a deal breaker if I can figure out everything else.

Thanks!