Call companies like Master Power Brakes or
Stainless Steel Brakes and a proportioning valve
specifically for that combo.
   You can also use the dial type "proportioning
valve", which is really just a pressure reducer.  It's
a lot cheaper and easier to install, but doesn't work
quite as well.

My 65 came with manual disc front/drum rear, but over the years the
oem disc were scavenged. They were replaced with after market front
disc, with a dual reservoir and power (glad I added the power).  I
stayed with the rear drums and for a daily driver, I am quite
satisfied leaving it that way.

A.  Definitely you want the dual reservoir unless you are trying for
concours. It's a modern safety upgrade.

B. You only need the proportioning valve, and I highly recommend the
adjustable over the fixed.  There are units which serve multi purpose
(proportioning and distro).

C. You can stay with rear drum and upgrade at some point in the future
if it's a money situation, or convert now. There are advantages to
staying with the rear drum, but much depends on how you intend to use
the car.

D. I didn't do it yet, but I would recommend upgrading the front brake
lines to steel braid due to some issues with rubbing/wear of the
rubber hoses.