helpful thread, as i'm currently in the same boat, came to a dead end with my baldor servo drives and controllers as they dont play well with others, so no motion board readily available.
i have a bunch of allen bradley servo drives but they are serco interface so motion boards are scary expensive.

come to the conclusion that picking up some closed loop nema 34's and controllers might be expensive but by the time i have mucked around with trying to find solutions for what i have its actually not that spendy to do things right the first time.

UC300 is the one I'd go for these days if running Mach3. Normally I'd recommend CSlabs controllers because they are superior in build quality and reliabilty but they are not supporting Mach3 any more and don't seem interested if you have a problem. The UC300 as more than enough I/O for most machines and works well enough with mach3, it also as it's own softwate UCCNC which works much better than Mach3 now and is still supported. Fit it to a decent BOB like the UB1 and your sorted.!
i cant seem to find a reasonable supplier of these in the eu could you recommend one.

Jazzcnc, i agree on the motors and controllers as that seems like a fairly elegant solution and the money saved on power supplies is best spent on better motors and controllers.

do you have a schematic for connection of these motor controllers to the UC300 ?

last few days have been a bit of a head scratcher, initally i wanted to use the spares i had and when that went under i felt the centronics boars seemed a good solution however the closed loop board they supply is over £2k so by the time i add a bit of aux io its nice but way to spendy, i did however like the option of adding a linear enc input for additional axis which could have given me closed loop on the steps and feedback from scales on the other 3 axis.

would you say that the uc300 and the nema 34 motors from aliexpress plus mach 3/4 is the way to go ?
as you have done a few of these your experience is way more than mine in this respect.