No way a "stock" 327 (and that is a bad word) can turn 8000. Modified valves, springs and cam, then it can! Heck lots of engines can turn 8000 with the right "valve stuff". The question is: Will they live? And 327's WILL blow up if you keep doing that high rpm.
"Rotary valves" on a piston engine. They took a stock 302 Ford, bolted on the rotary valve heads and spun it to 10,000 rpm with no other mods! As was mentioned, piston "speed" as it relates to stroke length is also a limiting factor. But I still say, VALVES are the primary and first problem area.
Web site on "rotary" valves. First tried WAY back in the early 1900's.
http://www.coatesengine.com/products.html
The "wankel" rotary engine COULD turn higher rpm, BUT consider this. This is a "stock" engine with a warranty in a "regular" car and it turns 8000 plus rpm???? DAM, name ONE other "stock" showroom car that will turn CLOSE to that range! AND still be "factory" warranty covered? Thats awesome rpm!
Only ONE car comes to my mind. The new Honda S2000, with it's tiny motor (think theres a connection there with small enigne\high rpm?) I THINK tjhat motor comes close to 8000 in it's "stock" form. Therefore, with mods, I bet it would turn 10 plus!
Ernie