Proportioning valve question

up to some year the disk / drum proportioning valve was a separate valve mounted to the rear (6 inches or so) of the distro block in the rear line.

there is a later year ( 73???) distro / proportioning valve combo that might bolt into the same location as your distro valve with only minor movement of your tubes.

If it was me I would opt for year specific parts, less issues down the road.