I use Cambridge TBC bushings from johnnycnc. I have an old B mandrel and Cambridge bushings you can have if you can use them. Mandrel MT adapter isn't included but will work if you have either (1) an adapter which accepts 1/4" X 28 threaded rod or (2) collet or similar chuck to hold the rod (B mandrel is 0.2875" diameter).
PM your address if you can use it.