When the 4-bbl was installed on my 318 (about 5 years/3,000 miles ago) the original timing chain and gears were replaced with a SUM-G6603 double roller chain/gears. I also had a new water pump (Cardone 8-vane) installed.
The engine is going in to be rebuilt in a few weeks. Can these components be re-used on the new rebuild?
Yes. Do it if you know it's somewhat new stuff. If the chain is loose on the new stuff... you'll know what to do, replace it or implement a tensioner for 40 bucks.