Keep the ball bearings! The roller bearings that are sold tend to be made of Chineseum. It is reccomended to change to roller bearings with a disc brake upgrade. You can often find the roller bearings on sale for $69 on feebay.

I reccomend converting to disc brakes, as the truck will stop much faster and straighter with the discs. 1954 drum brakes did not have automatic adjusters, so you can expect to readjust the brakes every 1000 miles or so.