Thanks John, I actually walked into the local AC Delco distributor and gave the D1312C number you provided and the service guy told me I wouldn't see it for about a month. Fortunately I found the AutoZone part number and after I picked up the first one last night and confirmed it was a B28, I ordered a 2nd one which I should have by Saturday for my original 480 which will remain on the shelf even though i completely cleaned and reserviced it including reskinning so it looks great!! oh well. BTW, picked up a small tube of moly grease for the grease well at a local hobby shop for $5.
As for the B28 I picked up last night, stuck it in my DavesSmallBodyHEI this morning which although I specified 6"-8" of idle vacuum when I had Dave build it, he supplied with a B26 can, (VC1808 or same as VC1765/B20). so with full manifold vacuum the engine would hunt around and idle would surge and drop and hunt and... you get the picture. Because of this for the last year, when I put Dave's SBHEI in service, I've had it hooked up to ported vacuum.
So, like I said, Installed the B28 this morning, reinstalled the distrib, set static timing to 8*, hooked up full manifold vacuum to the can and the car runs great!! Crisp throttle response, stable idle, significantly less to nill gas fumes in the passenger compartment... nuff said!!
So with 8* of initial, total timing @ 3200 rpm is 37*. could probably stand some more initial but runs great and starts right up as set now so there it will stay!!
I know this subject has been beaten and rebeaten over the years but...