I "roller cam" means that the lifters are equiped with rollers. The standard way would be for the lifter to slide over the cam lobes instead of rolling over them. The roller cam is better because of less friction and roller
cams can be designed differently. Roller cams can have a more aggressive lobe profile the a non-roller setup. What this means to the driver, is more power with good drivability. There are alot of cams and related valve train components available due to the popularity of the 5.0 mustang. Any used 5.0 or 302
is a good swap candidate, just take off the fuel injection stuff and add your headers, intake, carb. Use the
front cover from your early model engine and a early style water pump. The outside is the same between the 289 and 5.0 (302).