[olddog]

Well the cost verses benefit on the roller cam is a personal choice.

At least in theory, the roller lifters allow a steeper ramp at both ends, thus the valve can be opened quicker and held open longer (because it can be close quicker). So a roller cam is the solution to your problem. It would act like a bigger cam, without sacrificing manifold vacuum. Again you have so many cid to make power with, you may not need or want it.

I haven't a clue what gearing and tires you are running, but I'm surprised you can hook that monster to the ground.