Dave,
I've thought about the Wayne option along with the nice valve cover from Clifford. I can't help you with actual fit, but my conclusion was I can't afford those right now. I've spent too much money on everything else. So, I went with the cheapo-chrome from one of the usual vendors. They showed up and I'm quite happy with look and fit. I'll have to get back to you on leakage rates in about a year.
If you'd like, I can send a picture. With all the lines and hoses that are going to have to run between the valve cover and the t-stat housing, I'm thinking of going with one of those spacers also.
David