How are 28-29 and 30-31 radiators different?

[CabrioletDon]

Boy, am I frustrated! I've spent a lot of time and more than a few pennies recently trying to get my '30 Cabriolet correct by replacing the front cross member including pulling the engine/transmission, welding up holes, setting all new rivets, repainting the frame, etc. Re-installed the radiator today...and it does not seem to fit correctly--it's sitting too far forward with about 1 1/2" inches between the radiator and the forward end of the water pump/fan shaft. After some searching at various vendors, I see that there are two versions of radiators being sold, one for 28-29, and one for 30-31. Since I've changed the front cross member from the incorrect 28-29 to the correct 30-31, do I get a new radiator as well, or can I make the old one work? Besides the mounting holes, are there other differences? I'm not trying for a fine-point car, but am trying to do everything I can correctly. Would appreciate any advice or direction!