My Punch-Out was converted to a Time Killers when I first got it, though the Time Killers boardset was gone. Fortunately no permanent damage was done. I had to replace a lot of stuff to get the stink of that game off though (marquee, wiring harness, power supply, control panel [the original PO CP had been Swiss-cheesed]).
It is a terrible game, brought to you by the same people that later created "Street Fighter: The Movie". Try it in MAME if you've never played it.
And like others have said, this was a kit game. No such thing as a dedicated Time Killers machine.
If I liked the type of cabinet it was in and everything was in good shape then I'd probably pay $150 for it. It wouldn't be home to Time Killers for long though.