I

an,
I've also done a similar conversion using the Scorpion but leaving it as a Scorpion with resin boxes that I have made but not r/c. Just doubled up on the sprocket and idler wheels. R/C wise the Scimitar uses three channels of my 6 channel radio. I am currently using two marine esc's I had going spare and a servo to enable the gun to go up and down. The gearboxes are standard Heng long and work fine although I am tempted to use a mixer esc from Action electronics in the future as I have a two channel Hi-tec unit as a spare. I have doubled up on the first set of driving wheels and fitted spacers on the others. I also fitted 1/8 wheel collets to hold the wheels in place from another hobby of mine. I also doubled up on what would be the sprocket wheel at the front. It seems to work ok without dropping a track even in a sharp turn.
If you've got an old Scorpion doing nothing in particular it's worth giving it a go, but not sure how it would work if you've still got the grey waxy tracks. Not well I expect.
Dylan