I have a 1937 LaSalle and installing a 500" Cadillac engine. I don't have the dimensions of the (huge) radiator at hand but it appears as though I can either install two small electric fans or one large one on the back of the radiator. Will I still need a fan on the engine and a shroud over it? My preference is to not run a fan on the engine. I'm wondering if I can get by with the electric units.