I have an 82' with a 305 w/AC--(torn out.. but..it had it at one point) as a running project. had a few problems with it since the day i got it, but, I'm a service member, and hardly have the time to dedicate to the project.

temp sensor doesn't work---no clue about how it works...

spedometer doesn't work (lower spedo cable.. but how to do it....??)

over heating - replaced coolant, radiator, thermostat, and hoses. Car is fine when continually running, but stop and go or really hot days = overheat. I think it might be the heater core, but heat works ok in the cab, but when i'm driving and i make a turn, i get blasted with really intense heat until i'm out of the turn. Usually, about 15-20 min cool down with hood popped, and a little wd-40 down the carb, and it starts right up. also, when it does over heat, the lower radiator hose is generally cold, compaired to the radiator intake hose. any suggestions? if it is the heater core, how do you unclogg? or replace?

The first thing to check on the temp sensor is that it is plugged in. It is located on the drivers side between the first and second spark plug. It should be a green wire.
Speedo cable just unscrews at both ends.
Sounds like a radiator that has seen better days on the overheat issue. Heater core won't fix that. No idea why it gets heat when you turn.
Thanks for your service. 5th Army 68 - 71. 62 bravo

For the overheating, I would be leaning toward the Fan Clutch, since you are cooling OK unless you are stopped. Heater core would have nothing to do with the overheating- in fact it actually helps to remove some of the heat. Also, do you still have the fan shroud? Very important to the cooling process.

As for the heat when you turn, there is a Flapper Door that is designed to "Blend" hot and cool air entering the HVAC system. The bracket that makes that door open or close is a weak point, and tends to break. In a turn, that door could fly open, and you would get full heat until you "Closed" the door by turning the other way.