They are generally good guns. I personally don't think parkerizing looks right on AK's, I would go the Duracoat route or if your cheap -like me- you could shoot it with some appliance epoxy and bake it on. That works well and looks pretty good. If the paint on yours is like mine anything would be an improvement.
If you want to put wood on it it's not hard. There are 2 little "nubs" inside the handguard retainer to hold the metal one in place. They will keep the lower wood from fitting right. Some folks grind them off, I just took a bit off the front edge of the wood handguard with a file and it fit right in.
You can use any gas tube afaik, I used a Polish one, but it has to shortend and then the cut end has to be opened up a bit. I just carefully cut mine with a hacksaw and gently hammered progressively larger sockets into the end to slowly open it up. Took about 10 minuts and it works just fine.
Also instead of welding the brake/extension on more just sbr the thing and ditch it altogether!
Original furniture:
With wood and slant brake: