If you can afford it, go for the Mesa 7i95, it is a step/dir controller with encoder feedback and since your drives have encoder outputs it will make for a nice machine with two control loops. Overkill?

Even if you get the 7i76E, you can later add a 7i85 or 7i85S (i still do not know which one, one is stepper the other is encoder, i am referring to the encoder one) and again have two closed loops, one in the drives and the other in LinuxCNC.
Some more questions:
-did the drives/motors come as a set?
-do you know if they are tuned for those motors?
-since you can use the software to control them, did you check if the pins on the encoder connector are set to step/dir?
In general very easy to have them working, if they are a set most probably they are tuned already, chances are they are set for step/dir already, so some wiring and a quick config is all it takes.
P.S.
You keep mentioning payment, this is an open source software forum, we all help here as much as we can for free, so no need to insist on it, mainly because we do not have time to think how to spend it !

But if you still feel the urge to buy us a beer or two, i can provide the crypto addresses !

P.S. on the P.S.
You will get the same help anyway through whatsapp or other "face to face" methods, it just might take a bit longer through the forum.
The crypto thing is a joke.
Yes i do use crypto.