I agree the 12" wide rims and wide tire look awesome. A benefit to you is the early birds can fit some rather wide rims in the stock wheel wells. I a pretty sure you can squeeze a 315 in there ask NOTATA (#14 car) as he has done so I believe. I am not ruling out taht I wont make future mod to the car, just right now I needed to start somewhere and get a good base line for the current mods vs stock and then the future will have those mods vs current if that makes sense at all.
just to avoid confusion, by 'stock parts' , a better definition would be a part that is readily available with a wide selection of aftermarket support. ie Z06 mono block calipers light years ahead of 1978 parts, yet are for the most part readily available should you need one in a crunch or need replacement parts. I was not nesseccerally referring or stating that I would like to use and keep all the parts from 1978 if you catch my drift.
the Kore3 kit (front and rear w/o rotors , calipers or pads) was around 1200 shipped. it is a superb kit and Tobin is extremely knowledgeable in brakes. I don't know how they compare to the baers as I am looking to use Porsche turbo or GT3 calipers and rotors. these are made by brembo. another company that I would consider is StopTech. You can alway go to Alcon if you really want top notch brakes and empty your wallet

. In any event, to change calipers all you have to do is obtain or make brackets for the calipers to the spindle or rear backing plate. the good thing about the above mentioned companies is, as far as I am aware, you don't hate to by their pads as they are common items and you have a wide selection of manufactures and compounds.