Do you have a Facebook account?
Log into your FB account and do a search for "Vintage Holiday Rambler Owners." Make a request to join the group. It is a very interesting group of owners of old HR RVs. One of our members is Doug Klingler, son of Richard Klingler, the founder of HR. Doug is very knowledgeable and could probably answer your questions.
I also like quality vintage RVs, and have a collection of 10, including 3 Holiday Ramblers. A 60's HR truck camper is something I've been lusting after for several years, but they're few and far between.
Looking forward to seeing you over at the FB group.
curmudgeon: noun; a crusty, ill-tempered, irascible, cantankerous old person . . . .
79 27' Holiday Rambler Statesman, 78 32' HR Imperial, 85 36' HR Imperial 5th Wheel