With a true box stock predator with rules like SPG predator rules you will not be anywhere near same gearing as a clone...usually best place to start is to find out what people are using on the unrestricted clones at a certain track and use one size bigger driver gear than what they are using and go from there. With a predator, 5800-6000rpm is gonna be your peak rpm to aim for, if you have to leave the governor in place then rpm would be closer to 5200-5500 in my opinion. It would absolutely have to be a momentum track to use a 19 or bigger front driver on a 1/5 track, seems like that is just too big of a driver. On our 1/5 mile tracks we use 14 or 15 driver and 60-65 rear gear on box stock predators, unrestricted with no governor, turning 6200-6600