It is not possible to convert a game from mod to non-mod. This has always been the case with Civ4, and as far as I could tell was the case for Civ3 too.
As soon as the HOF folks release a new 3.17 mod version, we can upgrade to it.
Frankly I'm surprised it has taken this long to get that 3.17 version.
Well, maybe HOF is not what it was any more. So I say we scrap it, if possible.
. .