Looks like you've got a 3/4 ton there. It will have a 4.57 rear gear ratio (and an outside chance of a 5.14) which will make it slower than a stock 1/2 ton. There are no aftermarket faster gear sets available. Since you mentioned you are doing a restoration and keeping it stock, there aren't many options.
Your truck will do 55 to 60, but you wouldn't want to stay there for very long. You can try to find the coveted 4.10 third member from '68 or so to '72 (do a search here for more info) that will help some. I think some guys have swapped the 216 cast iron pistons for aluminum pistons on a rebuild to get a few more rpm's. I'm sure you'll get a lot more suggestions.

Steve

'49 3800
'52 3600
'57 3100