A quote from the shop will help you decide. Might be pricey to restore that one... others on here might be able to advise on the likelihood of fixing the existing radiator.
Aftermarket options are pretty broad.. just be sure it's the correct application for the slanty.
A good flush of everything to include the heater core and block along the way.
Lots of opinions on fluids. My preference is Green fluid 50:50 using distilled water.
