Flowkooler water pump for 340 going into a 1964 plymouth valiant

it lists the core thickness as 2.25" but i don't know if that accounts for any stand off from the mounting brackets-- if there is any. the technical data doesn't show that detail.

anyway, the best way would be to install the radiator, install the pump and then measure the distance and select a fan clutch based on the room you have left.

if the motor is in the car, and you had the radiator sitting there, you could take your measures or mock everything up and know for sure.

but, because it's the old style waterpump, and it doesn't have an extended shaft along with the reasonable thickness of the core on the radiator, i'd hazard a guess that you'll be fine with a low profile fan clutch.
The technical data doesn't show it, because each one is different because they come from CHINA and they have no rhyme or reason as to their assembly. And unfortunately, most of them are assembled in such a way as to move the radiator too far towards the engine on the brackets and take precious space needed for any decent clutch fan setup. ESPECIALLY with the China made three row radiators. I had a three row Champion in Vixen for a while and although it fit and worked, the fit was HORRIBLE. I hated.