With correct stock steering geometry, there will be no bump steer. Bump steer is caused by faulty steering geometry. Going to a rack will not fix that, nor will adding power steering.
On the ram assist power steering, while it keeps the stock steering essentially intact, exept for addition of the ram and the different drag link, a major "against" on it will be the cost. Last time I priced one, the kit was over $700, and that did not include a power steering pump.
