Digging around in RockAuto with different model years and such yielded a Standard Motor Parts vac can.
In the RockAuto listings . . .
1971 Chrysler Newport 383 #VC167 Advance starts at 10.5" Hg ALSO fits 360 in same application. The Buyers' Guide listing goes back to 1968 and up to 1972 for various models.
#VC187 Advance starts at 10.5" Hg 1972-73 and up to 1978 on some truck chassis models 360-400-440
#VC188 Advance starts at 8" Hg 1975-78 400-440
#VC189 Advance starts at 7" Hg 1975 Newport 360
(I looked these up for Chrysler models, but they'll fit Dodge, Plym, Imp, light truck chassis, as applicable)
I looked at a 1965 Dart 273 V-8 listing. #VC155 Advance starts 7.0-9.0" Hg Buyers Guide has listings from 1960-68, including 1962 Valiant, which would be Slant Six. Many large Dodge and light truck chassis listings. Plus 1968 Road Runner and '65-68 Satellite.
I suspect many are similar, with the main differences being when the vac adv starts (which might be adjustable via an Allen wrench through the vac nipple) and the total number of advance degrees.
They ARE out there, possibly not for a specific application, but obviously something close enough to work decently well. There was NO mention of points or electronic ignition, although model year breaks might determine that. The later listings were for "Exc Lean Burn".
Sometimes, you have to read between the lines with some "common" parts for older vehicles AND have a working knowledge of "product knowledge" rather than what's on the printed (or electronic) page.
The Chrysler dual-point units would be the cast iron Prestolite distributors, in the earlier years and aluminum housing by the time the 440 6-paks arrived with one.
So, there's you some numbers to deal with without having to resort to a restoration parts vendor and possibly higher prices. After all, THEY have to get them from somewhere.
CBODY67