What will your brakes be used for? Street, drag, auto cross?
For stock replacement calipers, Wilwood has some really good choices.
If you currently run power brakes, I would go with the 2.75” Cast Iron Wilwood calipers. Cast Iron will deflect way less than the aluminum alternatives and give you greater clamping force with the larger 2.75 diameter piston versus the single 2.5” diameter or twin 1.62” diameter pistons. The 2.75” big bore Wilwood caliper is slightly less (4.3lb versus 4.6lb) than the single piston aluminum version. The “R” version of the aluminum calipers is only 1lb less than the cast iron, 2.75” diameter piston. I do NOT recommend the twin piston calipers because they will generate substantially lower clamping forces over the 2.5” and 2.75” diameter piston calipers. As a reference, stock replacement, remanufactured calipers are around 6.3lb per caliper.
I looked into aftermarket bolt in lightweight rotors, but there is no lighter bolt in versions. The higher quality rotors from Wilwood, AFCO, etc. MAY offer some weight saving over NEW stock replacements because they are fully machined. Some of the stock replacement, auto parts store, the lower price rockauto.com caliper choices MAY not be fully machined in NON vital and NON used portion of the rotor (mainly the area between the rotor surface and the wheel mating surface).