Being an arcade machine owner myself I would probably go down the following steps ...
IF all the SFII artwork is in good condition & you like it .... keep it.
If it is in poor condition or you dont like it consider replacing it with new side art etc. Places like
www.mamemarquees.com have a good reputation for producing quality replacement artwork at reasonable prices. Or you can look for NOS [new old stock] but expect to pay more for it as a general rule.
If you do decide to replace it then have a look at whether a different games artwork is more appealing as I find the artwork of the old shool arcade games like Q-Bert, Donkey Kong etc is imho much, much nicer than the Street Fighter type art .... but that's just my opinion.
Here's where things get contentious ..... MAME it. My only reasonings here are ....
1. Arcade pcb's are old & getting older by the year. EPROM rot is slowly killing boards off [not an issue if you have an EPROM burner and the know how] and latert SF2 games etc die if the lithium battery conks out.
2. The money spent on one arcade board could get you a whole PC for a MAME setup. And it is more reliable to boot
3. Buying arcade boards off EBAY etc is fraught with peril. If they say "tested perfect" dont believe them until you see it running yourself.
4. You need a new monitor anyway .... and 15 khz tube monitors are crap as if you mess with one it can bite back ..... lethally I might add .... and the issues with degaussing,picture shift over time etc are downright anoying. You can get 19" LCD monitors that accept 15khtz off HAPP etc and are open frame so they slot into a cabinet no problems and wont kill you if you make a mistake.
Lastly .... all those 48-in-1 and 1066-in-1 arcade games are running MAME anyway under cover of a custom frontend. But they lock you into proprietary hardware which is under powered, cant be upgraded, and the frontends are in some cases UGLY!!!
Additionally, all the 48-in-1's etc sounds totally crap for games like Gyruss, Scramble etc. Honestly .... MAME kicks their asses from a sound & accuracy point of view.
If you were the proud owner of a mint condition, original Moon Patrol or Scramble cabinet I might have a rethink .... but SF cabinets are dime a dozen out there ......
Anyway .... just my thoughts for what its worth ....