Chances are, you would have a hard time finding the correct Big Block eng., to go back in it, but then, there's also the pretty commom 366ci. G.M. Truck Big Block, that was used for many years. Plenty, of those still out there, & if this truck is indeed full air brakes, you can probably find one still in a truck, that has Air Brakes, complete with the Compressor. If you get the right rear axle ratio, as Mike stated, you will have no problem, running the Highways, at good modern speeds. The 1960 Chevrolet L80 Spartan LCF, I had, was completely stock, but would run 70-75mph easy. It had the orig. 348ci., Big Block, with Full Air Brakes, Factory Power steering, 5 spd. trans., with 2 spd Eaton rear axle. I can't remember what Mike's top speed is, in his 1957 Chevy Heavy Duty Fire Truck, but seems like it was a modern speed also.
