The mechanic we had help from when we restored the car recommended the MSD set up that he apparently runs in all of his cars. I built most of the car when I was 15-16 and if I could go back I would change a lot of things lol. But anyways, the crank pulley is 6.25" and the water pump pully is 8", which matches the firebirds part catalogue you had linked before.
The coolant mixture is 50/50
Changing the thermostat and having the radiator cap checked will be a project for the weekend. I'm also thinking about pulling the water pump to check the gap on the divider plate, but we'll see.
When the engine is up to operating temp, the fan is not any harder to turn than it is when the engine is cold. Is this a symptom of a bad fan clutch or improper setting of the spring?
The engine timing curve I was referring to is just the one that correlates with the spring/bushing combination currently in the distributor. I've never had the car on a dyno, but I did take it to a mechanic that specialized in old Quadra jets and had him tune it.