I had a set on my 440 for about three years. The quality seemed OK and I didn't have any issues with them. However, after reading a few first-hand accounts of them failing over on the Unlawfl Race & Engine Tech board, I got a little worried and ended up buying a set of Harland Sharps. You may want to post on the Unlawfl board and get some more feedback.
Good luck.

"When I'm in a slump, I comfort myself by saying if I believe in dinosaurs, then somewhere, they must be believing in me. And if they believe in me, then I can believe in me." - Mookie Wilson