Took the car out on a hot day and found that I was leaking coolant. Had to run it for quite awhile again to determine that it seems to be the waterpump. Didn't really leak much again but went underneath and the weep hole was wet. I got what I believe is the right pump. the short snout. Anyhow, I was talking to a guy who suggested I also do the timing chain. If it makes sense, I am for it but I'm not convinced it is necessary. The car has 29k miles so I would only do it if I expected issues simply from age of the car. Thoughts??

How much slack is in the chain?

The guy you were talking to does not know much about Pontiac timing chains, he is probably thinking about a SBC timing chain set up.
The Pontiac timing chain (although not difficult) is a whole other procedure that has nothing to do with the water pump, unless the timing chain cover is also leaking coolant.

^^^ what he said.

At 29k I wouldn't even check it unless its a no name brand and car is driven hard....

The guy I talked to was concerned that they get old and brittle (gear perhaps). He was saying something about plastic. Anyhow, the car has original chain and 29k original miles. I am planning on just replacing waterpump. Thanks for the input.

Some engines came from the factory with nylon coated timing gears to "quiet" down engine noise. It's been a very long time since I disassembled my 400, but I am thinking Pontiac did not use nylon timing gears on the V8's??? Others experts will chime in.

On the other hand, the 351 Cleveland 4 Bbl in my 70 Mustang had a nylon coated gear and it was falling apart when I tore that motor down in the early 1980's

I didn't do the work when mine failed on my '68 400HO in 1974 so I can't say for sure. However, the mechanic that did the gear and chain repair then said the failure was because the nylon-coated gear got chewed up and the chain had jumped several teeth. .

I replaced a timing chain and gears back in the late 70s on a 69 GP and about half the plastic was gone
from the cam sprocket but it had not jumped time yet so I caught it in time .
I'm not sure all motors got the nylon sprocket They started using them in 65-66
I beleive GM quit using them in 77 or 78

Didn't realize 29k original miles.
In that case I would replace it with a Mellings timing chain sprocket set.
Seen many of the nylon gears give out back it the 70's without much advance warning.
My 67 400 4spd stripped the teeth around 40K in 1981-82.

Pump is off and I am getting ready to install the new one. I see that the thin housing behind the pump also has a gasket. I did not order that gasket and was not expecting I would need it. The thin housing is popping off slightly and obviously, the gasket is no longer sealed. Do I need to remove and replace this gasket??

You should replace that gasket and their is 2 tube seals behind that plate that should be replaced you’ll see them after you get the plate off
You don’t want to have to take it apart twice

Ok. Thanks. Now I see that the catalogs say two gaskets required. Should have realized this. It is the same gasket correct? I also see water pump sleeves with seals. I assume these are the tube seals you are speaking of. I appreciate the info...definitely don't want to take it apart again. I was however, surprised how easily it did come apart.

Yes gaskets should be the same and yes pump sleeves and seals
Yep the water pump comes off pretty easy even if it’s the first time doing it
Clad to help
Good luck with rest of job