if my opinion is welcome...
first, medusa heatsinks can be bought seperately:
http://www.medusaproducts.com/accessories/heatsinks.htm
the 36mm ones are usable with 36mm motors [apparently].
second thing to notice, the traxxas heatsink has smaller fins, and thus it`s a lot easier to mount and use than the medusa one. all other dimensions are equal between those two however.
http://www3.towerhobbies.com/cgi-bin...?&I=LXJD62&P=7
i have been using those for years without any issues/interference...
the 36-60-2000v2 is a killer motor at 5s. a tad on the slow/conservative side at 4s however [it will need gearing up quite a bit]... so suicideneil got it right on with the 24/58 gearing: it should get you to 40mph approximately [with 4s and assuming 'close-to-stock' wheels/tires]...