simple, take off the radiator cap and look in the hole. You can see how many rows it is.
The shroud is specific to the width of the radiator so if you buy the same width then it stands a good chance of fitting. My mustang seems to have had the radiator replaced once with a 65/66 one so when i bought a shroud for a 67 it would not fit so i had to buy a radiator too. The shroud will do more to cool your car at a stop than just about anything else.
When you open the cap with the engine cold, you'll see the radiator coolant. Drain enough of the coolant into a clean container to allow you to see the radiator cores. Count the rows of cores. Now you know. Funnel the coolant back into the radiator.
If you go with a Griffin, you'll likely not be able to fit your fan shroud. Check with Griffin when ordering it. The ones I've seen are thicker than the copper/bronze radiators and when mounted will be closer to the fan. The aluminum radiator is a lot more efficient and so the shroud should not be needed.