Difficult to "restore to original condition", but not impossible. Comparatively few M1s are in original, as-new configuration, due to their military life. It's not reasonable to expect that anyone rebuilding the rifle would have said "I cannot use this stock, Sergeant. This is a Springfeild stock, and I am rebuilding a Winchester"
The parts should
not be blued, hot, cold, or otherwise. They were given a phosphate finish typically called "Parkerizing". Doing things to the crown...not needed. The rifle will most likely be more accurate than you or your Pop can shoot it anyway. maing one from a kit...well, it depends on whether or not the parts are USGI, reproduction, who made what...it all depends
Without even getting to the parts you need, let's take a 'regular' complete M1 as an example
It's been through arsenal rebuild(s). Parts were changed. On an M1, what looks like serial numbers in many cases are drawing numbers. Some parts, like follower rod forks, were swapped out during WWII or just after. The parts that were removed were very seldom retained. My own M1 was made in 1944. It does not have several "original" parts anymore, and I am the very first civilian owner of that rifle. The missing "original" parts were removed and replaced by regulation at various times during military maintenance and/or rebuild
Another example on my own M1- the rear sight. Mine is post-war, and is, technically speaking, a superior sight to the original. That's why it was removed and replaced by the US government when it went through arsenal rebuild, like most were. The 'correct original type' sight will set me back 150-175 dollars
Your Pop won't have swapped out parts, but in order to have "correct original" parts, he's in the same boat as me- potentially paying a premium due to the scarcity of those parts. The follower rod fork is classic example; "short forks" are rare, while "long forks" are not. They do the same job but one is less prone to problems
A correct US Government issue stock with correct original cartouche stamps that are proper for his rifle... Well depending on what year the rifle was made, this will cost some dough, big bucks or maybe not so big bucks but still, original cartouches are very desirable
Try this link:
http://www.thecollectorsource.com/