Company is still around to my knowledge. But I have a promega that has been pretty converted. The basics of the CoreXY G-Code should work for most part need to make changes to the endstops on the Z. config.g
I recommend reading the RRF3 differences and get Pin calls at the bottom for the Maestro
https://duet3d.dozuki.com/Wiki/RepRapFirmware_3_overview
If you do what I did...I did one line at time looking up in the Overview if it changed..if it did followed the write up if not moved to the next line. All the M98 calls just need " " around the file name for it to work again. I would recommend pulling the data back to the main config and get rid of some of the calls.