Not on Firebirds or GTO as eBay ad states. These were found on the big cars, so in my opinion, the pricing is optimistic.
1968 400 Coupe, verdoro green, black vinyl top 1968 400 Convertible, verdoro green, black top 1971 Trans Am, cameo white, auto 1970 Buick Skylark Custom Convertible 350-4(driver)
On some sites those are shown to be about the same as #215 heads. Besides having small valves, they also have press-in studs. But, that don't mean they can't be used in hp apps.
I bought a '74 Ventura drag car which had a 455 with #215 heads. It ran 7.30's at our local 1/8 mile track. So, the engine was makin at least 400hp/500 torque.
Yes, there were better Pontiac heads made. But, the #15 heads can be used for hp builds, if done correctly. Doubt he can get his asking price tho, especially with the high shipping charge.