I unfortunately can't help you with where to buy them, but I certainly agree with you about liking them. I have them on my 32 and I love them. I just added a picture to my album to show you the B&M ones that I have. I get a lot of compliments on them and they are a "large" or big block style that look different on my SBC. I just put a little permatex on the top of the sides so that the top piece seals nice. I don't have any leaks.
Just thought you might like to see them