Indeed, get a full fixed stock. They are hollow so flex along their length and reduce recoil to your shoulder a lot, even with the rigid buttpad. They are simple, so a non-german contract one is just as good.
If a collector, fine, but if you just want a shooter, be aware there are collectors. Most non-HK parts are not "knockoff" but "contract." Turkish and Malaysian and other such guns have Germans in lab coats overseeing things. They are fine, and authentic enough for me.
I suggest the Buffertech buffer. Works very neatly, and as I always say: the spring-and-pin buffer is a last-minute fix to the early CETME/HK rifles when the rubber buffers failed in service (I MAY even be able to get a photo of the originals in a couple weeks when I am in Leeds... hoping!) so an elastomeric buffer is sensible, and helps again a bit with recoil. I and friends I have who have used it do NOT screw it in. Should work just dropped in and it will stay in the back of the receiver anyway. (Bad reviews I have seen are for clones and US built receivers which says more about the clones than the buffer I say)
Read up on bolt gap, etc. Get feeler gauges, don't guess. If getting out of spec it can do bad things to the gun, and also will make it less pleasant to shoot. Get new rollers if you need to adjust it, and do this soon.
Scratches on the claw mounts are nothing: get yourself a claw mount and scope that up!
That ejector buffer is not standard, but presumably worked to keep it clean. Normally the brass spins around and smacks the receiver with a nice little crescent of brass mark for every single time you pull the trigger.
Look up the cost of that trigger. Assuming you can prove it is factory, it MAY be so beloved you can fund dressing the gun up more by selling it, getting a normal trigger group and have a lot of cash leftover. Do not underestimate how insane the collectibility goes on HKs.
I mean, such that I don't want a G3 now (I do have a 33), and if I ran across this in a gun store I'd buy this without hesitation, shoot it for a week, then sell it for a profit, without even trying. $2,000 is a deal, maybe a steal for these now.
Get a refrigerator coil cleaning brush. Like this:
https://www.amazon.com/GE-PM14X51-Coil-Brush/dp/B00DZU954E Useful for lots of things like cleaning mag bodies, etc. but invaluable to get the receiver tube on stamped HK rifles cleaned up.
