If you don't turn your six above 5500-6000 RPM the roller tipped rockers are not a necessity even though they have some advantages over stock. However on a higher revving engine like a 170 CID they are very beneficial for adding durability.
Sorry, almost everything in the quote above (not the entire post, just the quote) I disagree with for the following reasons.
Roller rockers are not needed on anything period!
RPM has NO play in determining what style of rocker is needed. Just strength.
Moving away from a stock rocker to an improved design and/or stronger rocker will improve durability over a stock rocker. Though at stock engine specs, anyone would be hard pressed to prove they will out last the OE part.
You could very well produce that same power and most probable, equal the longevity with a mechanical rocker vs a roller rocker at every point.
(Edit)
The draw back of any aftermarket rocker is material used. Durability and overall weight. If the mechanical rocker is heavier than the roller rocker, it will show less power during a dyno pull. An amount you’ll never feel and see at the track.
