Nice video Gary, if you are not wanting to use a cordless drill you could use a transmission from a rock crawler
http://store.rc4wd.com/ this is what I’m thinking
http://store.rc4wd.com/Disruptor-Ult...ck_p_1206.html with a 540 motor possibly 35T
http://store.rc4wd.com/Engine-Motor_c_26.html these motors may be a little small for what you need in the 250 so possible an MFA motor and planetary gearbox would work well and cost less
http://www.mfacomodrills.com/gearboxes/940d_series.html