How much does that Muggy weigh? Must be getting on for 10-12lbs I would've thought. I think that motor is somewhat on the small side really- just about enough fora maxx basher, but the muggy/lst is alot bigger, so you'd be better off with a 1515 sized motor. That said, if you are going to gear down then maybe it will work fine for a good 20 minute run or so. As for gearing/voltage- check the calculator out, it never lies!
5s would be good for bashing, 6s for a little more speed with that 1700kv motor; gearing will depend on the diff ratios, which I dont know off-hand (enter them manually into the calculator and then choose your spur/pinion ratio to get that 30-35mph you want).
http://www.scriptasylum.com/rc_speed/_top_speed.html