Snafu,
It sounds like you got a pretty good deal on that as long as it runs well. The receiver is made by Imbel but, may be either inch or metric magazine cut. If it has a little slice milled into the rec it's metric. If it has a deep uniform slot then it will take inch mags. The rifle sounds like one of the post '89 pre-94 rifles brought in by century with the plain crown. Does it have the thumbhole stock? If not you may want to check fo US made parts to ensure 922(?) compliance.
If IN doesn't have their own ban like MA, NY, NJ , etc. you can prob pick up a folder but, that is an involved project. You would need the whole lower which is mainly the trigger group, a diff bolt carrier, top cover, stock.....these parts add up quick. Moreover, IIRC they are somewhat more fragile than the fixed stock set up. I'd keep it fixed stock, possibly add a muzzle attachment and any US parts needed to comply with the letter o' the law and shoot the hell out of it.
The best place to learn is www.falfiles.com
the link below has a whole bunch of stickied threads, some of which will cover century guns
http://www.falfiles.com/forums/showthread.php?s=7e4702229df8e383d8dc08c8f0d950aa&threadid=60277
good luck,
Blitz