Ok, I don't know where to start except to say that's a bad idea.
The 462 is a
MEL engine, which is a different engine family from your 429, which is a member of the 385 engine family. Exhaust is the least of your worries. The 462 has the MEL bolt pattern, and your C6 transmission has the 385 bolt pattern. You will need to swap in the C6 from the donor car. Which leads to:
The newest 462 was manufactured in 1967, which means the donor transmission is also at least 55 years old and maybe as much as 63 years old. That family of engines was produced from 1958 to 1967, so
parts are going to be hard to find. Which leads to:
How is a 55 year old engine with over 100,000 miles considered fresh? I can think of several adjectives to describe a well running mid-60's engine, but fresh is not one that I would use.
Even if you are getting the 462 for free, you will end up paying more to make it work than just selling it and buying a 460, which is another engine from the 385 family and it is a direct bolt in replacement for the 429. Well, you will probably have to tweak a few things such as accessories, but that will be minor.
Edit: the 462 was produced in 1966 and 1967. So your 462 could only be 55 or 56 years old. I'm guilty of not reading the link I included above. Sorry about that. They included the 462 in the 1968 model year Lincoln, but they were left over from the prior year's engine production.