Back in the day, comics would get cancelled that way all the time, with little or no warning. Today, the cancellation notices come months in advance, but in those days, the business was a little more cold about it--often cancelling books in the middle of extended plotlines, or even in the midst of a story arc. There were no write-in campaigns to save the book, no fan outcries. Just the end.
Given the quickness with which these decisions were made back then (especially by the notoriously cutthroat Marvel), there probably was a scripted, pencilled, and lettered Further Adventures #35. There was probably substantial work done on #36, in fact. And we'll probably never see much of either of them. There are hundreds of unpublished comics out there, but most of them leak to the public in scraps and pieces; there's a major effort ongoing to restore a comic from the freakin' 1940s. The restoration effort started over 40 years ago. It can take that long. The pages get split up and auctioned off by the companies or an enterprising intern, or even the artist himself. The scripts get tossed in the trash. Readers rarely ever get a chance to see much of the full product.