I put a 283 in my 1957 Chevy truck. I used the stock 6 cylinder radiator mounting with a fan shroud. After various overheating adventures (probably nothing to do with the fan shroud and fan spacing)I ended up making a bolt-on frame from 1 inch square tubing to position the radiator close to the fan ( a little less than 1/2 inch). After finding a lot of ambiguous data about the re-location of the radiator for a v8 with stock components, I came to the conclusion the factory appeared to use different radiator mounting structure, not just moving the existing mount structure back. I could be wrong about that, but in any case, making my own mounts works for me. The plastic after-market shroud fit poorly for me and just didn't look good because of that. The fan shroud approach should work though (as per red58), my little journey with the overheating problem got me to making my own mounting frame. FYI: the over heating problem turned out to be 2 bad thermostats in a row.
