You can go bigger if you wish with a truck block due to the taller deck height. The 496 that I built is using a standard passenger car block as far as running on regular gas not a problem as long as you choose the compression ratio accordingly.
If you will be leaving any BB Chevy idle for any length of time at all it is a good idea to go with a roller cam, BB Chevy’s in industrial applications that idle a lot tend to flatten their cams. As far as pulling long distances the added torque will let you pull down in the RPM range making it an excellent choice for this type of work.
