I've though of the same thing for a long time but in 5.45x39 - no BBL change just a modified bolt mag and recoil spring, I think there's enough 5.45x39 rifles out their to make it worth while.
If it was an Auto gun originally yes you need the compliance parts, if not your good to go. Here's a place for milled receivers - http://www.cncwarrior.com/firearms-parts/receivers/ak-receivers/
Go with the lithium grease, it cleans up easier and faster - you won't have little black grease spray all over you if don't get the wheel bearing grease totally off the rifle when you fire it.
Here's a letter I just sent I.O. (Ohio Ordnance) about my PPS 43 - c
I recently got a PPS 43-C Polish Pistol & took it to the range and It stove-piped every 3Rd round or so and the empties would get cough behind the bolt, some times as many as 2 empty rounds would be back in the action ? I...
You know the older we get, we think were getting smarter but in my case I see missed opportunities, back in 72 I could have gotten a Thompson for under a thousand. In 82 under two thousand, now they start at 12,000 and up. DAM!!!