I have a 1969 Firebird convertible getting painted right now. New interior gets put in when that's done. Then its time to look at the engine. When I bought the car last year, it was a driver with a spare motor that had been pulled because it overheated at stop lights. After reading many posts, I'm leaning toward it having the wrong water pump or the spacer hadn't been "massaged" to fit better. The water pump has been changed. Either way, I have it on a stand and the car has another 350 in it that is a dog. In running the numbers, the one on the stand appears to be a 1969 350 HO with "48" heads. Different carb, distributer and water pump has been changed. I'm hopping it has not been touched internally. Plan is to pull it apart next fall and see what I have and what it needs.
Reason for this post is from what I have read, there are not too many of these around and this might be a chance to answer some questions and dispel some myths so if anyone has a question, or a comment on what to look for when pulling it down, feal free to post or send me a message.
Of all the Pontiac forums, this one seems to have some members that are really smart and know there stuff.
Not sure where I'm going with the distributer. One in it is not OEM, it's HEI and I have heard of clearance issues. Hell, I don't even know if it works. The other thing is the carb. Have read that I need one that is factory correct and I will be happy, but those are hard to find and lots of $$$ so we shall see.

Congrats on a '69 convertible. But even more if it is a true HO car. That is really rare. This chart shows the #48 heads as big valve 10.5 compression.Pontiac HeadsThere are many reasons for it to overheat so I would check the basics first.

Original is always best, but, you can use a different carb if it has the right jets and rods inside. I prefer a post 1973 Q-jet because I can convert it to electric choke. Look up your factory carb specs here> Carb specs

If you open the engine, check the cam out for sure. The Wallace Racing site has the cam codes too. And block codes.

I prefer the HEI distributor. No points maintenance, hotter spark. It is a tight fit against the firewall, nothing a small sledge won't correct. You can bench test it by clamping it in a vise and rigging it like it was in a car. Just watch out for the spark. It can reach a foot away and bite like a MF.

Thanks for the tips. Im just guessing water pump because it has been changed. First thing is to verify it has the proper one.
Car was not an HO car, but that was what was in it when the previous owner bought it about 20 years ago.
For a second I almost thought of building a "tribute" TA, but so much has been changed from stock, Im just going to make it what I want. I'm having the painter put on the HO stripes from 67,69. We will see how that goes. Interior is getting redone, just back to factory but it will be new.