A couple of thoughts...
First, with the right rear end ratio there is no reason a 235 won't run your truck down the road at highway speeds, provided everything is in reasonable condition.
Second, you can tell a 1/2-ton from a 3/4- or 1-ton by the number of lug nuts at each corner. Six means 1/2-ton. Eight is a 3/4- or 1-ton.
Third, a 283 was an option in a '58, so your 327 could look stock in that truck with a little work to find the right parts.
