I didnt read much of the other replies, but the Source Rockers use to be roller bearing... I would avoid these like a plague...
Look at these...
http://www.kmjent.com/cart/product.php?productid=445&cat=11233617&page=1
Id try these on a hyd, or small solid engine.

[color:"red"]65 Hemi Belvedere coming soon [/color]
[color:"#00FF00"]557" Indy engine 1.07 60ft 144mph in the 8th 2100 lbs package [/color]