Some of these rules will go for any collector piece, and some are specific to the 4T.
1. Buy quality, and don't be afraid to pay for it. The 4T is not the kind of gun a novice should be 'fixin up', and if the price seems too high today, look back in a year or three and see what they cost. All matching 4Ts were $125 35 years ago, $500 10 years ago,$1100 5 years ago, and a nice one will go in the $3000-$4000 range today. So if you do pay a little too much, not to worry. You'll get it back later.
2. If you get quality, take care of it. We only pay the token amount for this kind of material so we can temporarily possess it. Eventually, it will move to the next owner (unless you get buried with it). The next owner will be thankful you did.
3. Get the scope purged. If you know a FCS tech in the military, he can do this for about the price of a six pack; otherwise pay to have it done. This will prevent the growth of mould inside the lenses. The scopes were good quality, but it has been a number of years since they were in military service and had this done. To check for mould, look through the scope, but focus on the lenses, not the picture through the scope. It will appear as a cauliflower type growth on the inside of the lenses.
4. When you see that 4T that you have always wanted, put away the rose coloured glasses. Learn what to look for to spot a fake. You've bought the books, so put them to use. Don't buy into stories that explain away defects like: The army didn't keep the scopes and rifles together always; if one had to go for repair, it was replaced with another.
5. If all else looks good, I like to guage the condition of the Enfield by how well the barrel rests in the barrel bearing. It should take a nice lift (3-6 pounds lift) to get the barrel off the end of the wood. If pulled left or right, it should return back to the bottom center of the bearing area. Forearms can warp over the years, but just as often are changed and not properly bedded. The bedding is critical if the rifle is expected to deliver it's peal performance.
6. Get all the accessories for it, hopefully with the rifle. The little steel box for the scope is getting to be around the $400 mark these days, as is the transit chest, and the origional scope bracket. The leather sling, in good shape, runs $100-150. And the scope itself will set you back more than $1000.
7. And as Badger Dog said, show us all pics. The Enfield addicts always love to see another example.