Just a quick update..
I tested out the bar's I've had made up to fit the EV2 Mk4/ FTP900 and they are indeed the same fit - so the bar's and carrier plate etc for my 3D hook will just slot straight into either an FTP900 or EV2 Mk4.
Waiting on the Carrier plates to be printed now (today hopefully).
I reckon it'll add about £20 to the price of one of my hooks to have the UKNeil bar and new Carrier plate (the carrier plate volume is bigger so it costs a little more to have it printed).
Then all I need is someone to with an FTP900 or EV2 Mk4 test it out for me.