If you take a look at the Indy Lit section, I'm sure you'll be able to find some stuff on the Further Adventures, however I'll answer the question the best I can as I myself have asked the question a while back and Stoo did answer it.
In Volume 1 of the Further Adventures (which covers Raiders adaption and 1-12 issues) Marion's in Raiders (all 4 issues), #6 (which is about the Raven's Nest nightclub), #7, #8 (my personal favourites), #9, #10, #11 and #12. So that's six issues of Marion appearances from June 1982 - Dec 1982. It is implied in most of these that the adventures take place in late 1936, though with the state of the timeline at the moment, I'm more likely to lean towards 1937. The comics don't always state the year in the intro.
As far as I can remember she also appears in #16 and #17 (whichever are the Search for Abner issues, which I am looking very forward to in Volume 2) and there's more I'm sure before her last appearances in #22 and #23 (which I look very forward to seeing in the Omnibuses). The later ones would have to be taking place in 1937 and would work within the years discussed in the Ultimate Guide and in KOTCS.
You can also look at TheRaider.Net's Lit section. They cover all the synopses and covers for the Further Adventure and Dark Horse comics.