You going Racing or Show (or a bit of both like myself?)
I'd say the Lower Control Arms are worth the investment. You have to cut part of the Mustangs lower control arm if you want to be able to run 255's up front.
I'd go Powder Coat, but I'd have it done at a local shop for less money (and clean the limited weld splatter up before hand that FFR does do.)
If you want some show in there then here's my Short list
Anodize your Alum. Panels,