The x-factor would be a better option just because it has a 4-link suspension and a bigger(torquey) motor. Just use savage stub axles on the x-factor and you can run any maxx size tires, my sugestion would be 40s and either of the treads they offer for them. You really dont even need a good cyl. head unless you need to lean it out for more power, but it should have the grunt. Definatley go up 7-8 teeth on the spur, or use a savage spur and stock clutch. Talk to dirk diggler he has a rock x-fac.