Depends on what you want; USGI rebuild mixmaster, CMP rebuild mixmaster, parts correct, or period correct. I have done a complete spring job on all my Garands and Carbines as soon as I got them. On my recent Springfield I only swapped its HRA trigger group for a correct SA group. On my Danish return Winchester I went a little further and swapped the op-rod, hammer, safety, front sight, and bolt. While not 'original' these two rifles now wear mostly all correct drawing number parts for their age; 6/44 SA and 5/44 WRA. I have the parts up for sale as I don't need them, and in five years of owning Garands I have never had anything break..knock on wood. If they don't sell, no big deal; I have a bunch of spare parts.
T