Disc brake Caliper pins/bolts sizes????? Where to buy???

the 'cuda calipers will have 2 3/4" pistons,the A body up 'til '75 are only 2 5/8"(slider style)
this will produce higher pressure and much better braking
i think it jumps from about 3600 psi to 4400 psi at the caliper.
i have '73 cuda discs on my '70 Duster as well.