Don't know about the dual circuit master, but if your emergency brake is in good working order and adjusted correctly you should not have a problem. Brakes rarely completely fail without warning. Check lines for rust, wheel cyl & master cyl for leaks, and check fluid often and you should never have a catastrophic failure.

Just something to think about. Good luck, and let us know if you find something that will work well.

Tad


1946 Chevy OS 1.5ton, 1955 GMC 3100, along with other various IH,Ford,Nash,MGB,.....