Take top off the factory shifter box. Wipe off grease. Have a helper hold the shift lever up in the Low-Reverse position and weld tab into low/reverse slot. Put cover back on and cut off old 2nd-high lever. Make a shift rod that runs from old low-reverse arm at the shifter box to the auto trans selector arm. Since you are keeping the factory steering box your done. Some want a start in park only safety switch which can be made with a water proof (boat) starter button mounted on firewall and a tab to activate on the shifter arm. We NEVER use a selector indicator since the shift pattern for automatics has been Park(doesn't move)--Reverse(goes backward)--Neutral(coasts on an incline)--Drive(goes forward) for 50 years and if they're too dumb to not know this we don't want them for a customer.
Picture of an S10 conversion using the AD factory shifter and has the safety switch.

[img]https://i.postimg.cc/JthHy9sy/S10-055.jpg[/img]

Evan