Which Kadee Coupler?

My recommendation would be to the 745.  If the TM model is like other recent MTH locomotives you may to trim the back 1/4 of the plastic kadee gear box to allow the loop on the truck to clear as it swivels.  Otherwise, they are a piece of cake.  If you don't already own #812 height gauge I would highly recommend it.

Same directions work for the 805 series couplers, just that the gear box is metal and cutting the back 1/4 of the gear box off is a little more difficult. But not a showstopper by any means.

The last and most likely the least desirable would be to just use a short shank coupler and gearbox (806 or 743).  No cutting the gear box, just works.  Depending on the radius on your railroad you might find the short shank couplers a little fussy.  IMO, that is why it's better to use the medium shank couplers and normal gearbox (with a slight modification).

"almost equal to the C&LS TM version" 

Hardly!

"for considerably less money!"

True.

Ed

Get a pack of 745's and a pack of 743's. Try the 745's with the backs of the boxes filed down first. If the truck's coupler mount clears the back of the box you're good. If not, you'll have to resort to the 743's. GP35's have such a short clearance on the rear I had to use the 743's on the rear.