Hi Don,
Poor Enigmaticul thinks everything we're talking about is small like his set up. It'd be one heck of mount to put a 15 lb treadmill motor on the back of a Taig headstock!!
I am running my metal 3-in-1 combination lathe with a treadmill motor and a MC60. Motor is rated at 90V, 17.1 amps, 2.5 HP - there's plenty of power to go around and the controller stays cool, but I also mounted the controller to a piece of aluminum to act as a heat sink and there's plenty of air circulation.
The KBIC-120 is a workhorse too. I use one to control my cue lathe. I'm thinking either one is going to be sufficient for your boring setup.
Remember they are sized to run a treadmill that has been tilted up to ~15 degrees with a 300 lb woman on top trying her best to be next years Victoria's Secret Top Model - now THAT will cause that motor to pull a bunch of amps.
Neither of these two controllers are that expensive, so make sure you have a spare in case you do blow something up. At least you can quickly get running again, though maybe not at the load you were trying when you blew up the controller, but you won't be dead in the water either, while you look for a better solution.
And of course, you can use a simple 5K variable potentiometer on either to dial in the speed and a DPDT switch to reverse the direction of rotation.
My 2 cents,
Gary