here is a stock plate for the outside of firewall MC area with a stock manual brake rod = rod 7" long.
you can get an adjustable rod from mancini. IIRC
I made an alum plate used larger bolts bolting it to firerwall and then 2 bolts thru firewall to a alum 2 bolt MC = stock mc from vac brake bosster.
IMHO I would use the alum 2 bolt MC over a cast iron MC.
I weighed all of my delete and add ons shaving a full 200lbs off the nose of my 88-440truck going manual steer/manual brake/alum intake/alum wp housing/ mimi starter/mini alt/ heater box delete/weld rims
