Roller rockers. What do you know of these

I have a chance to get a new set of these RKM roller rockers for 200.00 The person that has them bought them for a 340 only to find these were for a 440. Does any one know any thing about them? Good or bad. here is a link to them. List is 340.00 so it would be a deal for me. The bottom link is his car he has up for sale as well. Sweet duster
Thanks

Rockers
C.A.T.

Duster
http://losangeles.craigslist.org/ant...727510104.html