Large valved 273

With the bigger open chamber of the 340/360 head u loose compression. So now 10.5 is down to 9ish to 1. So in effect u have to try to fill up the gaping hole u created. For that to happen u would need a Hemi type piston with a bump as big as ur fist and deep valve reliefs machined into them. Which may or may not be feasible. Kim