Replacing single reservoir M/C with dual reservoir on four wheel drum system

Bewy said

The bore size of the dual m/c needs to be the same size as the single m/c. So that can be measured or obtained from a service manual. According to my Motors Manual 1960-64 Ply Val used a 1" bore m/c.
No proportioning valve needed. With drum brakes, 'proportioning' is done with the wheel cyl size & the width of the brake shoes.

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Thanks for answering my question about the proportioning valve.

According to this, the bore size of MC36412 mentioned in one of @slantsixdan's posts is 1.031". Close enough, or not quite right?

I'm hoping for a specific recommendation that will bolt up, require no changes to the push rod, work without power braking, yada yada. A direct swap (after splitting, of course). Any help, anyone?