Save your money, get a 86 for dE350 master. It is a damn near direct swap and it will lock up the 3/4 ton calipers and 40" tires on my jeep no issue.
all you need to do is drill out the mounting holes on the master to 5/8" (will double check that diameter) and grind down the lower edges of the mounting flange and it will bolt right on. Use a couple conversion fittings and start testing. you will have to adjust the set screw on the end of the actuator rod to get the master dialed in 100% but it is way cheaper and better than a wilwood master, plus any part store can get you a rebuild kit for $8 if something happens to it.