I have a NABCO master cylinder that I am going to use think it is off a Colt. Dual circuit with a .700 bore.
figure to have to use a proportioning valve with this mix of brake parts but am not over worried about it.
I had thought to use a servo [actually have a new Lockheed in a box] but decided to go dual circuit so that pretty much ends any thoughts of a servo on the SV.
The Toyota calipers are pretty common and the parts house will most likely have a set on the shelf, the bolts are on 3 1/2 inch centers.
Had give up on figuring out how to put a set of cheap 4 piston calipers on an Alpine but your post and the S3 I just got that is minus front calipers sparked my interest again. Located a set of Volvo calipers today at the junk yard so tomorrow I will see if I can HB them on the car. I had forgot the volvo units have two lines feeding them but that will be cake if I can over come the bolt spacing.