That would be a good idea, since you're on a non-original frame. You can drill holes wherever you want for fenders, even in the stock locations. I would ask Mar-K for a template or at least measurements of the stock holes, unless you have original bedsides to go off of. That would be the easiest way to adjust for a different wheelbase. You can't move the front fenders in relation to the cab without a LOT of work. You would have to consider the running board to fender location as well, because I believe the running boards bolt to the rear fenders like they do on AD (47-55) trucks.
