The only knucklehead kits were the 1/8 scale Revells, The L.A. Street chopper, and a Drag bike. The Panhead, was also a 1/8 Revell, and also the Revell 1/25 scale . it started as a parts pack kit, then later released in "Grease" (the movie) packaging, where it was a two pack and came also with the Honda. Unfortunatly, these kits can get pretty pricy.
Also the 1/8 scale kits all share the same bottom end and cylinders as the Shovelheads.
I like (and have) all the others you mentioned, I would like to see your builds.
That WLA45, sure is a nice kit also, Have you seen the civilian version (WL) of that kit, it is also very nice. I actually have a 1:1 1942 WL45.
If you would like to see my version of the Knuckle check out my Fotki
Nice talking to you, hope this helped some