Hi, and welcome to A-P!
To answer your questions:
1. The new HAS will support stereo via the JAMMA edge. Your MV-1C can be stereo modded, but the stereo audio won't go through the JAMMA connector, rather via an AUX connector, like the 3.5mm jack. There are guides for this, or you could have it professionally modded for you by JNX
@XianXi
2. The Framemeister is great, so far it's got the best compatibility, but it adds much more lag than the OSSC (which is pretty much lagless). For the time being my suggestion would be to just use the XRGB and see how you like it, perhaps it's just enough for your needs. For the XRGB you won't need the Scart cable, an 8pin mini din to 8pin mini din cable will do (like this one -
https://www.ebay.com/itm/Mini-Din-m...-male-Cable-/371509293392?hash=item567fadf150). Don't worry about damaging your scalers, the HAS makes the signals safe for your equipment.
3. All quality arcade PSUs will do the trick. Personally I like the Mean Well MWP-606 or SUZO 42PP0606.
4. The CPS2 I/O interface comes with the ATX and 6pin VH connector (the same as used in the HAS), so if you get an arcade PSU, you'll be set.
5. We have a very cool Arcade-Projects branded JAMMA extension harness which you could buy instead -
https://www.arcade-projects.com/for...e-projects-jamma-extension-cables.7833/page-1 or
https://www.arcade-projects.com/for...sion-sets-with-has-kick-harness-support.7832/
Thank you for the prompt reply! A-P is awesome! I had trouble signing up on the forums because my email was weird and not 1 or 2 but 3 mods got together to sort it out!

Sorry for the Neo Geo related questions but it took months for my account to be approved on the Neogeo forums, and after reading a bit there I became a bit frightened.
1. I looked into the JNX consoles and messaged him about one but seems hes backed up to 2021, so I went the DIY route instead. If anyone still has a link to a reliable how-to about the stereo mod I would appreciate it. I looked briefly on youtube but most videos were very old and not well shot.
2. I see the 8pin din you mentioned but that would require me to change out the plug!

I like a "set it and forget it" approach. My FM is connected to the gscartsw. I might go your suggested route until I find a alternative I like then.
3. I will grab that Suzo model then. I originally was researching AES vs. MVS, which led me to iffy board revisions of the AES and hassles involved in getting them properly RGB modded, which led me into MVS consolization, then to the whole debate about those aliexpress consoles, the always out of stock omega and JNX consoles, which led me here! I still aim to have some sort of supergun box with power supply and such imbedded in it just like you posted on a separate thread.
4. I signed up for the CPS2 I/O board you sell in preparation for when I eventually get around to the CPS board stuff. Briefly researching that, seems a whole other set of issues. All that A+B board nonsense, revisions, g chips, hdmi mods, and Darksoft's mod for them. Atleast with your advice I know ill have the power supply before then. Thanks!
5. Didn't know this existed! Thanks for the link. Does the length at all effect anything? I think the 60cm might do me but maybe I should get a short and long one incase I do make some housing for it...
Also thought of another question:
6. Is there a list somewhere where I have to set the voltage when hooking up the supergun to a different board? I saw someones videos earlier in this thread displaying a how-to and showed to hook the supergun and board together before turning on, and starting at the lowest power setting and going up from there to 5 volts.