rear trailing arms

[thingman1]

I will be puting bigger tires on my car and would like to keep the tires in the middle, I was wondering if I could cut my arms add 1 1/2 to them in the middle or would it be better to just order arms that are already made. Money does have some to play with it all, but I want a good ride and easy maintenance of the car, when its time to repair things on the rear I want it as it would be if it was just stock. I have most of my plans maped out best I can for not have my car near to look my plans over, I am kind of getting parts together and then once I have my Thing start to put it together. Since I will be coming up from Texas to Washington state I am picking up parts to do it all, just need this last part to really get my rear lift maped out.