I think I'm going to declare my internet research finished before it started. The answers I found were basically what I expected, and it all leads to a grand total of "who the hell knows." Here are the facts...
* My comic is the victim of a bindery defect called, predictably, "wrong cover." It is by all accounts a rare occurance.
* Though I have been unable to find evidence of any other comic like mine, it is generally accepted that bindery defects are seldom if ever one-of-a-kind, which makes sense. In the case of this particular comic, since both the insides and the outside feature Spider-Man, it and its sister copies must have slipped under the radar.
* According to some guy who knows a lot about comic book production, comics that are distributed weeks apart could be printed at the same time. That explains how a PPTSSM could have an MTU cover, even though we all know those comics weren't distributed on the same week. (We all knew that, right?)
* As you might expect, very recent comics with bindery defects aren't valuable; they're just oddities. My comic came out in 1976, just on the cusp of the "Modern Age," so it might be just old enough to qualify it as a collectible. There are a handful of famous comic book errors that become valuable collectibles, and they don't have to be all that old. For example, if you were a Fantastic Four collector, you might obsess over the green variant issue of FF #110 from 1971, in which everyone on the cover was colored wrong:

* However, it's important to note that comics like the green FF #110 are well-known amongst comic book geeks, which is why there's a market for them. My comic is unknown and therefore a harder sell.
* My friend Kurt, a law student, is now flaunting the fact that he lies about everything, usually for no reason. Case in point: when he told someone about my comic, he changed "Spectacular Spider-Man #1" to "Amazing Spider-Man #50" and claimed I was now a millionaire. Thanks, Kurt. I can totally see why you had to do that. It's no wonder nobody believes a damned word you say.
In sum...
I could write to people who know things about comic book values, but I can already guess their response: it's worth whatever people will pay for it. That's comic book geek parlance for "damned if I know." So the only sure way to find out my comic's value is to try to sell it, which I may as well do. More on that later.
I have a guess, though. First of all, since the defect is called "wrong cover" and not "wrong pages," it's safe to say that my comic is, in fact, Peter Parker, the Spectacular Spider-Man #1 and not some crappy issue of Marvel Team-Up. Its bindery defect is rare, bizarre, and interesting, and best of all it doesn't detract from the comic's appearance or quality (some bindery defects result in a deformed comic, but not this one). That said, I suspect my comic will sell for more than the value of PPTSSM #1, but not much more. I would be very happy with a sale price of over $100, which would of course net me a 3000% profit.
PROFIT!!!
In a day and age where the infamous Billy Ripken "Fuck Face" card can be had for a mere $8.50 (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=60519&item=5142298303&rd=1), I wish you the best of luck.