Dave,
Did you use Earl's collector seals also?
http://store.summitracing.com/partde...0&autoview=sku
I have my exhaust off the car while installing the seats and seat belt mounting, so I'm going to re-do the gaskets. I used Sanderson's recommendation, but after thinking about it - and reading your earlier post - I'm going to use some decent gaskets. I like the look of Earl's header gaskets. I just have to make sure that they have a version for the Vortec heads.
By the way, the ports on my Sanderson headers (made specifically for Vortec heads) measure 1.5W x 1.875H. The ports measure 1.5W x 1.5H. The ports on the headers are a full 3/8" taller than the ports in the head.