What about for brain surgery or piloting a Harrier or traslating French to Chinese? Would you be upset if I assumed you weren't qualified to any of those things?
Just like brain surgery, building a set of long-arms is possible, you just want to make sure you know what your doing before you start cutting. Based on what you've posted you aren't quite there yet. Go and do some research like I suggested.
What did you expect from your post anyway, "ok so here's the deal, i want to make a long arm kit...well not really a kit but i want the RAD to have long arms under it, how hard would it be to make a set?". How hard is it? Is it a be-otch? You must be like 16.