Here's my Century STG58 built on an Imbel "R1A1" receiver. Put an Enterprise muzzlebrake on it, swapped out some crappy Century parts for an FSE trigger group, Penguin buttstock, US made gas piston, etc. etc. to make sure she'll run 100%. After a couple thousand rounds of break-in I had it refinished in a polished hostile environment coating. The gunsmith said this was the first gun he had ever attempted to polish using this coating, and it turned out fabulous as well as being very resistant to corrosion and scratches.
This my favorite gun of all. I call it my "cold dead hands" gun because there's only one way its leaving my possession.
Trust me, you will love your STG58. One piece of advice--don't crowd the iron sights the way you do an AR15 or it will bitch-slap your face like Diana Ross at an airport terminal. Keep your noggin midway along the buttstock and you should be ok.