Rear disk conversion issue

Those years of Crown Vic's only had one or 1.062 bore sizes. I would push bleed the system from the calipers back to make certain all the air was out of the system first. But what size bore did the SSBC universal master cylinder have? I think you primarily are down to a fluid volume issue at this point and that a larger bore size cylinder is in order. Most larger modern 4 wheel disc brake systems have at least a 1.25 to a 1.3 inch master cylinder bore.