Building a 273

IDK
Just cuz the 1.88/1.92s don't physically rub, does that mean that they are not preventing the valve from passing fuel-charge at some point or another during the opening event?
How much lift will it take to get the cone to form? IDK.
How little duration is required for that lift? IDK
What if the big valves lose flow with that wall right there? IDK. Without a before and after, how could you ever tell?

Ima thinking that a turbo'd 273 is looking pretty attractive right about now.... maybe even a two-stage. There you go; run any gears/any transmission/almost any small cam/ even open-chamber heads....... IDK

But Ima liking the Poly idea.