http://www.fordmuscle.com/forums/mus...ear-drive.html

This tells the story pretty well

In theory, they appear to be a good idea. In practice and for a daily driver, not so hot. Then - there's the annoying noise. Then you have an unknown manufacturer for this product - and is it a Chinese POS?

My choice for a performance engine now would be a Gilmer belt drive, but a good double roller chain and gear are the best bet and a well proven design for a SB Ford or any other normally rodded engine.