Ive got a Spal 305mm fan (the higher powered version) on my mk1 vitesse and Im very pleased with it. I removed the fan AND its boss from the end of the crank and it fits nicely. You might even get away with the thinner lower powered model or perhaps go up to the next size of 325mm. After trying various controls Im now on purely manual with a fused relay and switch supplied from the radio position of the ignition switch so I can run it for 30 seconds after engine stop without the risk of forgetting it👍