Dual Extruder Firmware help

Okay, here goes the full description.

I’m trying to create a custom firmware for a flexion dual that I’ve made a mount plate for. All the models are fine, but I was hoping to be able to tweak the Taz 6 Dual Extruder V3 firmware to make this print head work. The root problem is the print nozzles aren’t in exactly the same spot. Although I’ve taken measurements of differences and placed them in Simplify3d as offsets to x and y, the Taz still won’t home correctly as the nozzles no longer line up with the Z homing switch, regardless of changes I make to the gcode in the slicer.

I feel like the issue is the actual G28 code in marlin is hardcoded to particular offsets which are not changeable. I could be wrong on this, but that was my assumption. So next I watched Tom’s video on Marlin configuration and played around with Arduino. There are SOOO many settings I just feel overwhelmed. I understood and entered in all the appropriate information for the thermistors and board etc. but beyond that I don’t know where to start with telling the program how far off the x-0 and y-0 they head needs to move to begin the z homing, and then from there the bed leveling programming… holy moly. I’m not sure I have that level of intelligence. I was amazed I fixed my pool this last weekend lol.

Is there some way to decompile the firmware for the Taz 6 Dual Extruder V3 and tweak the code to do what I need for the tool head I’ve created? That seems like it would be immensely easier than figuring out how to duplicate nearly all of it. Suggestions? Help? Or just watch more of the videos on Marlin programming and figure it out? lol. Thx.