Has any one use a after market master cylinder like a Wilwood? And which one did you use? Have power brakes in my 66 putting big block in it but valve cover hits the brake booster. Wanting manual brakes, cam lift is over 650 lift anyways. Canít really use booster anyways.
Try a HydraBoost off of a diesel truck (assumes you retain the power steering pump to power it.). That is how most deal with power brakes and a cam with more duration than you need. It is the duration number not your lift value that causes your manifold vacuum to disappear. I ran a 0.759" lift at the valve with a 1.7 rocker but only 236 degrees of duration. It was a circle track cam not a drag racing cam. Made gobs of bottom and mid range torque to accelerate my car.
Standard height valve covers will fit over roller rockers running polylock adjusting nuts. But you either cut down the nut and set screw by 0.170" of an inch or you buy short poly locks from your favorite cam company. They all sell them as they all know the ones they include with their roller rockers will hit the underside of your valve covers (that is why they have the same part number you have now only with an "S" for short, or an "LP" for low profile after the part number). But they want you to buy their custom tall cast valve covers, even though you are not running a stud girdle. What is really annoying is their poly locks won't work with a stud girdle either which does require a tall valve cover. So you end up buying a different set of Poly-Locks either way.
It is almost as if the cam companies are sitting back laughing at you as they collect more money from you because they know what they sell you won't work.
Any way if the HydraBoost bothers you (due to it's looks) then consider dual nine inch diaphragms instead of one big eleven inch. If your cam is too radical for vacuum assist the dual diaphragms probably wont work as their combined surface area is still less than the eleven inch booster.