1 is not a correct sentence.
Well in used in this sort of sentence to mean 'very much' or 'extremely' or 'considerably' (as in 'well good!' used by teenagers).
If he is 'well past' 40 it means he is a lot older than forty. He has gone considerably past, that is beyond, the age of forty.
You can see that you can't describe someone as very much or extremely or considerably 40.