A bit confused with valve size

[Triple White 91]

Hi everyone,

I'm confused on the following topic. From what I've read here and other sites, gt40 heads have 1.84/1.54 intake/exhaust valves and the gt40 P's have 1.84/1.46 intake/exhaust. (Please scroll down at following address to see chart)

http://www.ford-trucks.com/forums/733179-gt40-head-id-how-to-id-non-p-gt40-heads.html

If so, please explain this in terms of intake/exhaust valve sizes why these heads are different?

http://www.tristatecylinderhead.com/catalog/product_info.php?products_id=40&osCsid=08743d36d15ad3290c45ff1ab437e1ea

How would the heads from Tri-State be in comparrison to these ...

http://cgi.ebay.com/ebaymotors/NEW-GT40P-HEADS-COMPLETE-SMALLBLOCK-FORD-499-00-PAIR_W0QQcmdZViewItemQQcategoryZ33617QQihZ006QQitemZ160237795191QQrdZ1QQsspagenameZWDVW

Hope this is not a dumb question. Just trying to gather the correct info before a purchase is made.

Thanks