Radio box, and the center plastic cover(that covers the center shaft) is different on the 2 also
Other then those you would be good to go the back piece, and front piece are interchangeable on the 2.

For the wheels might have to cut some of the side off the chassis as I don't remember the difference in size (I do got the slash chassis laying somewhere here, but would have to find it)

For your plan might be cheaper with the pede, and getting the slash chassis as the tires are the bigger cost IMO.

Cause if you go slash and get the pede parts you would need the pedes front, rear plate, tires(saw a set on ebay for $30 shipped), and a body which would run you $46 + the body.