1976 Dart Overheating and other issues

Update: ok well think the radiator bit the dust. Car runs cool so I think the flush and new thermostat made a huge improvement, but now the radiator is leaking. So I’m looking for a new radiator and will also put in a new water pump.
Don’t need anything like those BeCool($800??). My car is stock slant six. Just need it to be dependable.

Read up some positive reviews on Champion radiators and their American Eagle line. Considering this brand. Only problem is can’t figure out how I know what radiator is in my 1976 dart. 19” or 22” is what the manual says. Does anyone know? I only see Champion providing a 26”. I’ll have to call them. Also, there looks to be a transmission line running into the radiator at the bottom. Is this what is referred to as a tanscooler?

As for the water pump, any recommendations? I read a thread about no need for a high volume pump (flowkool). Any quality brand recommendations?

as stated before I’m just working with basic tools and don’t want to modify anything. Just replace and make the car very reliable.
If anyone has any other recommendations for something solid on a tight budget I’d love to hear them. Thank you.