When Chevrolet came out with the V8 in the 1955 2nd series trucks they relocated the radiator core support back 5" from it's 6-cylinder location to get it closer to the fan, that set up was used through 1957. Then in 1958 they redesigned the front clip and put the radiator in one fixed location and made up the distance between the fan and radiator with shrouds.
I agree with 3B, there weren't any spacers or clutch fans used back then.
Also, be careful using a Hi-Flow t-stat, part of it's job is to slow the flow down so the radiator can have time to remove the heat. Removing the t-stat can actually cause overheating in some cases. The only mod I'd do to a t-stat is to drill a 1/8" bleeder hole in it to allow air to burp out when filling the system (note, some new t-stats come pre-drilled or have a notch in the sealing surface to take care of this).
Mike B
