SCR motor control, didi-key scales and my new mill drill

I just picked up a grizzly Mill-Drill at an auction, with 2 Acu-Rite DRO's
and a fairly old Wood's SCR motor and controller.

What is the advantage of the SCR controller? Am I right to expect that I can
now control the speed and torque of the motor, and not ever have to use the
step pulleys again? When I convert to CNC that would be a good thing, no?

One fly in the ointment, is that the motor nameplate says that it is only
rated at 1/2 HP, and the new Grizzlies are equipped with a larger motor, I
believe 1.5 HP.

I have two DRO's, both two axis, but only one scale was included, and I
haven't had a chance to hook it up to see if it works at all.

DigiKey is supposed to have scales at $2 an inch plus the heads, but I could
not find any scales on their site that weren't considerably more $$$$$

I've been wanting a mill for a long long time, and I can't wait to start
making chips!

By the way, this auction had a BIG CNC machining center (Burgmaster VTC300)
that sold for $165!