I have an 8" lift on mine and 31x10.50X15 TSL Super Swampers, I didnt cut much at all but I extended the Radius arm 1.25" and got the perfect offset Tire, I have this lift on and EA81 car though, EA81 motors are great I put them in all my wheelers but EA81 Axles are very weak like scott said, also The Trans's are apt to loose Reverse, Ive been through 3 of them in my 82 Brat. There are a ton of things to change over to get it to work right with 31's but it can be done by all means , just do your reserch and youll be able to find a lot of what should or needs to be done...............
Jeff