Ambient 8bit music

I've spent countless hours trying to soundtrack my latest level. Here's the preview thread. The level is mechanical, lonely, and mostly dark. I can't get past the idea of 8bit ambient music, but I can't find any that will work. The main problem I have is that so many of the good ones top out at 3 minutes. The sections of my level would do better with 5-6 minute songs. This song I like at the beginning but it gets obnoxious at the end.

So, far I've looked at ccmixter.org, 8bc.org, and chipmusic.org. If anyone knows a good site or a good track, I'd appreciate the help.

I may or may not be able to create something similar to what you're looking for.  I do know how to use Famitracker, which, from the sounds of it, should be more than capable of what you're interested in.

I had a look, but I also had a lot of difficulty finding appropriate songs. You could contact PlaidShirts&BigSmiles and see if they'd like to make you a soundtrack (that's more appropriate)? Or, of course, take Ultigonio up on his generous offer.

Other suggestions:

Brother Android : I've only listened to the Hero Core OST, and I'm afraid dialup is preventing me from checking out the other releases. I have high hopes, though.
Goto80 - Bortabra : There's 55 minutes of music here that I imagine you could cut something good out of. Drunkenambient seems promising.
Bubblyfish - Translucent : An individual song, not hugely ambient, though.
Søren Lund (Jeff) - Cyberworld : Some of this guy's other songs might be good too, he made the music I used in the blue area of My Super Secret Basement and was happy to give permission.
Disasterpeace - Level : Six and Eight for example, start off well, but as the songs progress they may depart too much from ambiance for your tastes.
II - Sea of Ice : You might find something appropriate here, but like before, the ambiance often serves as a buildup to something more song-like.

Newgrounds.com or deviantart.com has some unique stuff, but it might take a while to find what you want.

Uhg, yeah, that is obnoxious.  I was all into it and it start random static screams at me.  Geeze...

Brother Android does a very good job with musical imagery. If he were to describe my level it would be lovely, but so far he hasn't. I checked out the rest of the suggestions. Many good pieces or starts of pieces, but not enough to fill the game.

I forgot about Newgrounds. I've been there before, while working on my masterpiece, but found it very hard to find what I was looking for. I was looking for something very different then, so I may have better results for this. I'm skeptical of Deviantart's music selection, but I'll look. Maybe I'll get lucky.

@ Ultigonio: I, for some reason, thought it would be easy to track this level. I originally intended this to be something I threw together in a few days. Not the kind of thing I would ask someone else to compose music for. I have trouble underachieving though, so it will probably be pretty good in the end. If you still want to make the tracks, I can send you the level. Enough of it is done that you can get a feel for each area.

I'm still pretty interested in tracking for this level, so sure, that'd be cool if you sent it over.  Honestly, though tracking something that long is no simple task, it's probably a lot less stressful by comparison to some of the other stuff I've been trying to work on.  It'll be a break, almost.  Besides, I find I'm much more efficient at music and ambiance than other things, anyway. 

Problem solved. Ultigonio is making the music and it sounds great so far. Thanks for all the helpful replies.