Hi Eric,
It will be interesting to see how you get on. I gather from the Yahoo 7x12 Group that the headstock for the "Hi Torque" variant is longer than the "traditional" one, and this is reflected in the spacing of the holes for the fixing bolts in your photos. As you say, not a big job to drill new holes and bung up the redundant ones.
I also understand that the brushless motor in the Hi Torque version may be shorter than the traditional brushed motor. Do you reckon your old motor will fit in the space provided, lengthwise? Even if it doesn't, I'm sure you will be able to devise a way of mounting it futher outboard, rather than half tucked under the bed.
Andy