Wow, 3500 rpm? Sounds pretty fast for a 6" chuck to me. Mine does 1800 and is fast enough for me. If you're turning something small enough to need 3500 you'd want a small collet chuck wouldn't you? You're also gonna need some good spindle bearings. I'm very happy with my KB's and would recommend them to anyone. To tell the truth though, I'm not technically motor savvy enough to advise you on whether or not it will do exactly what you want it to do with your motor. If it's a good deal & if it were me I'd probably try it & see. As long as you connect it properly, I don't think you can hurt it and if it doesn't give you enough power, I'd bet you could easily sell it or keep your eyes open for a deal on a Baldor type 180V motor to match the KB. By the way, did you ever hook it up to the original controller & see what voltage it actually runs at? Maybe it's running at a lower voltage than the nameplate says to make it last longer/run cooler?