Whats needed to fit roller cam into my 1971 340?

Whats your hp/car usage goals? As mentioned above rollers are good for all out effort, but can create problems, like you are running cast iron heads? Well you really can only get about 1.80" installed height for a spring without increasing the rocker shaft height. Which presents its own challenges. To be brutally honest I run solid flat tappet with an almost all out effort x head. I didn't move the pushrod pinch which is what is left on the table. If you are sticking with the iron head, i would go solid flat tappet. Aftermarket head is a different story. The bottom line is it can be tough to get all the benefits out of a roller using a cast iron head.