You should have no problem running it at normal highway speeds but keep in mind that with the 4:57 rear end you are winding the engine up and sucking a lot of gas. I would recommend installing an overdrive in it. It will make a much better truck out of it as it will get better mileage and the engine will last longer.
Fred


1956 3100 Pickup/Red/350/3sp OD/PS/Disc Brakes
1957 Bel Air Sport Coupe/Red/355/TH350/PS/Disc Brakes
2017 Silverado LT Single Cab SB/Black/5.3/6 Speed Trans
1947 Willys CJ2A w/F-Head engine