Well, might be a moot point for you now but actually yes I do have one of these adapter boards. I bought one a while back to play around with. They work pretty well for what they are, though they don't actually do anything to improve image quality. Just convert it to VGA. Here's mine running Mario 64 on a RGB modded N64:
I haven't tested all the other input methods, only RGBs. On RGBs it seems to not like higher resolution input. I have to blind select games from the 64 Drive menu because the 64 Drive boots to a 640x480 resolution. It might just not like whatever its getting though. I'll have to do further testing in the future when I'm not so busy.
RGB N64, nice! Plan on sticking in a JAMMA cabinet or something?
Actually not a moot point at all. I've learned a lot about these Neo Geo boards since I picked this one up, and now I'm running the whole thing off 5v. Maybe one day I'll build a full-on "supergun" rig so I can mess with other JAMMA boards (TMNT!!!) but for now, I'm stuck in a military dorm room with barely enough work space and light to even do any decent soldering lol. Anyway, I ordered one MVC game online, it just arrived today, but a few days ago, this -awesome- local (Korean) arcade owner gave me a copy of King of Fighters 99 and King of Fighters 2004 for absolutely free, but -only- after he had meticulously cleaned them both and tested them on one of his working machines, during peak business hours. Needless to say, I brought him a six pack next time I came to play some games! Long story short, all three games seem to run just fine on my hand-me-down board. All I get is sound, (hooked it up to a stereo, it sounds incredible) but I have ordered a video encoder. Not one of the nice, VGA out ones, just composite, but it'll do for now. If all goes incredibly well, I just might end up with one of those sit-down "candy" cabinets to rebuild. Wish me lots of luck with that one! Anyhow, around the 11th or 12th, I should have some pics of an ugly, but working "consolized" MVS 1F.