I have basically the same setup on my 49 3600. The huge difference I found was adding residual check valves -
I've deleted proportioning valves in other vehicles and could give or take the residual valves, but maybe because the MC is under the floor?? Who knows, but at least on my setup that made the difference between crappy brakes with poor feel and a tendency to lock up (and no, there was no air in the system - none); and brakes that functionally, I can't tell apart from anything else.
Also, (and apologies if you've already mentioned this) make absolutely sure that your MC pushrod is set correctly. I've installed several of these types of units and find that more often than not, the "universal" setups are shipped without that adjustment being correct. More than once I've had to machine a new pushrod to get that measurement right - the manufacturers don't seem to care.
