driving large DC motor questions

I have just finished converting the X and Z Axis motors on my 1979
Ikegai FX-25N turning center. I was startled by how much simpler the
modern RUTEX 90H driver cards are compaired to the original Fanuc 5T
electronics. My application requires me to be operating at the drop of
a hat , and what I like about the rutex / PC system I have built is
that for a few hundred dollars more I can have a backup 90H card ready
to swap out in seconds.



I also purchased a Rutex R991H (0-10 V output) to drive the Spindle
motor. the R90H drive cards do not seem to have enough output to drive
such a large motor. I also want to have 'electronic gearing'
capability.

Using the R991H requires me to leave the old Fanuc Vari-speed servo
drive in place , and that is something I would rather not do, As I want
all the components in the machine to be easily replacable.


my questions are

(1) is there a inexensive (0-10 Volt input ) , 15/20 HP dc drive that
I could use to 'upgrade' the 25 year old Fanuc 5T vari-speed drive.

(2) If I hook up a 90H card to the spindle motor will the card blow ?
is there a way to gang together several RUTEX 90H cards to drive a
larger motor ? or is there a simple amplifier for the 90H DC output ?

(3) also what is the used vari-speed drive worth ? would it pay to
sell the drive and perhaps the dc motor and buy a VFD/AC motor combo.
(I only have about $1000 left now that the wife does not know about)

Thank you anyone who responds.