jdrakeh01

The original Basic Roleplaying (1980, I believe) was 20 pages long. It's no longer in print, but you can occasionally find copies of it on eBay for a reasonable price.

True! But I know the identity of four systems conclusively (there were conversion notes for all of them in the archive that I procured).

SPQR is definitely a very likely candidate. Perhaps HR. That said, I now know for certain that four of the five systems were OD&D, AD&D, Arduin, and Runequest.

Excellent!

Oh, I got the big one (softcover). Title page has a copyright date of 2008. I know that there was also a hardcover, but I wasn't sure which came first.

Is the softcover or hardcover printing of the big gold book the most recent?

I'm trying to find as much information as I can about Steve Perrin's North Coast campaign. He mentioned it in an interview, where he said it had been played under at least five systems and I personally know that D&D and Runequest account for two of those systems. I don't know much else (yet). Any information you can provide would be much appreciated!