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Buy the M03M kit. Take out the spacers. Add your favorite Cooper Body.
Much better imho. The M03M has all the new suspension, bearings, etc. You'll have the best of both. If you decide the medium wheel base might work better you can just put the spacers back in.
At Fastlane here in KC we ran them yesterday and were very solid, and durable. We ordered the kit, the TA03 diff, universals, sway bars and TRF shocks. You can add hollow gear shafts and a heat sink if you want to "maxx" it out.