The wheel well size never bothered me as much as the fact the entire bed and fenders were designed for a 1955 model with compatibly designed front fender openings.
As a 12 years old car kid, I thought the stepside bed looked silly on the 1960 models, being too narrow and having the “old” fenders on it. Retrospectively it’s obvious all of the design money was invested in the new fleetside models, and the stepside models received a restyling budget of zero. I’ve read where GM management initially intended to continue using the 1955 rear fenders on the 1967 series trucks as well.
Here’s an earlier thread discussing the topic of restyling the fenders:
http://67-72chevytrucks.com/vboard/s...fender+opening