Here is my take...

540 is no problem, as you know-providing you have a "good" block..

I have sonic'ed a lot of Mopar wedge blocks. Never seen one that could possibly be bored 180 over to reach 4.5. Most are pretty scary after 4.375(55 over-the good ones). Although I have a freak block at the shop that might be able to go .090" or .100"?. While I have never actually done it, a 4-5/8" stroke with a .070" might be doable. It would have to be tall filled and even then it might be a time bomb. And I don't know how much more stroke you can get with the [Edited by Moparts - Family Friendly Site - Keep it clean] journal sizes and maintain the internal pickup. Of course you can move the pickup point a bit, but you do eventually reach a point of diminishing returns.

That being said, lets say 560" is about all you can hope for. And there are NO production wedge heads that will use it to its advantage, unlike Hemi's, canted valve big Fords, or BB Chevs..

MB