Just picked Imbel receiver rifle. A pretty good price I think. It has the ugly thumbhole stock and such. My question is what parts to change the easiest to make it compliant and bring it back to looking right?

You have no need to make it "compliant." You didn't manufacture that rifle so that goofiness does not apply to you. You need to determine if the lower is inch or metric pattern and buy another lower of that type that is already in proper configuration.

 

You going to shoot Heavy Metal with it?

I might!! I do love rockin steel.

Easiest is to buy a new lower and replace it.

The L1a1 pattern lowers that had the stud ground off can get a new stud pressed in or use a hardware store brass insert with moderate success if it fits well.  I recommend the press in as it will be just like factory.    The metrics I don't know of too many that were thumbholed and consequently have seen very little on restorations.


You'll likely need a new trigger plunger spring too if it's an inch gun.  Century had some monstrously large and long spring for their setup.  Probably a new plunger because century nipped the end off of them.

what about 922r compliance part count with imports manufactured

That's a debate that goes on whether you need to or not for changing parts out on an already built rifle.  

To comply with 922 (off the top of my head) you'll need 6 parts w/o muzzle device, or 7 parts with a muzzle device.  
parts that ATF say are eligible; receiver, buttstock, pistol grip, forend (2 halves count as 1), piston, bolt, barrel, hammer, trigger, sear., magazine body, follower, and plate.  That's just off the top  of my head though.  Guys building will often go the US made trigger, hammer, sear, the piston, US magazines, and often stock, grip, and forend in some combination.  Guys that want to keep them as looking like a nation's as issued rifle will of course go with the internals first.  

bolts I don't think have been done much,  I don't think any that have been made impressed the FAL filers.  

As far as 922 need to comply with debate, go over to FAL files and read the threads on the topic you will find with a search.   There are decidedly differing viewpoints on the topic.

I wonder if yours is an inch on a metric. If yours is a Century Inch gun on a metric receiver then you will find all sorts of British marks all over the rifle.  Lots of E superimposed on a D for Enfield.   Century used Imbels with several patterns;  some all metric, some with inch cut for folding charging handle, some with wider notch for inch pattern fal mags.   Fire control parts (US made) for inch lowers are nuch harder to come by than the metrics.  They're out there though.  

I like the inch rifles better for their ergonomics and history.  British, Australia, and Canadian, kind of India too they did their own bastard pattern.  South Africa, Rhodesia, Papua New Guinea, New Zealand also used the inch pattern rifles purchased or received from UK or Australia.