Get some photos..... I think Altered Beast was a kit only, which means that cabinet was something else prior. Maybe a "classic".
Next thing, if you buy it, JAMMA games won't work in it (nor will a j-pac). Sega used their own pin-out format.
Lastly, regarding the sound problem, KLOV has this to say about it:
Fixes
This PCB also suffers from the same problem as Shinobi, however the sound fix varies slightly. You still replace the custom Sega chip at with a standard Z80, however you replace the ROM at location A10, as opposed to A7 on Shinobi.
~Ray B