The CDR valve that NAPA sells as part # CRB 29445 is actually a Delco # CV910. It fits all the 6.2s and 6.5s. It comes with a 3 1/2" cannister and two short steel nipples - each 1" OD.
During the years, GM used at least four slighlty different CDR valves. All were the same diameter cannister, all the same inside, and all with 1" steel nipples for hose or valve cover connections. The only difference was the lengths of the nipples and the angle of bend in some.
By making one CDR with short 1" nipples. this vavle easily fits them all. So yeah, maybe you'll have to add 1" or 2" of rubber hose. Seems that's isn't a huge problem, is it?
I just looked on my shelf and I've got three different CDRs (in a pile of 10 of them).
The CV870 is GM # 25042246, has a 3 1/2" round cannister, and two hose nipples both 1" OD. One is 1 1/2" long and the other is 4 1/2" long with an angle.
The CV871 is GM # 25042443, has a 3 1/2" round cannister, and two hose nipples both 1" OD. One is 1 1/2" long and the other 3 3/4" long.
The CV910 and NAPA CRB 29445 has a 3 1/2" round cannister, and two hose nipples both 1" OD. Both are 7/8" long.
I've cleaned many old CDRs and they worked fine. The metal disk on the vacuum diaphram tends to get sludged up. You can take apart to clean, or - just reach in with a long Que-tip.