Good quality 1.5 roller rockers?

It is logical that the walk across the valve stem would be more with such and increase of lift over the stock range as noted. (Hence the thought that shaft needs lowering.)

FWIW.... I've tested the 273 and stamped rockers for rocker ratio up to .500" when installed on a stock 675 head and watched the contact point walk across the valve stem. It moves quite a bit. Yes you are right.....I shoulda taken pix!

IMHO, part of why the OP's contact patch is moving out so far to the exhaust side is that his lift is going so far beyond the stock lifts for which these were designed. The range of the 'walk' has a lot to do with the curvature ground on the pad, and he is going well beyond what that was designed for. I don't necessarily think moving the shaft is going to change the contact patch/walk width. To reduce this, the pad would have to have the curvature of the pad changed. (Ground towards the outer edge with more curvature, I think.)

But the curvature of the pad also controls the degree of slippage that has to occur between the rocker pad and the valve tip, which effects the side force on the valve stem. (Which a roller tip gets rid of.) So it is a compromise, and I would bet the 273 rocker's curvature is set for lower lift AND limited slippage of the rocker on tip for durabilty of the stock valves and guides.

Redesigning that curvature AND then regrinding the curvature would be beyond a backyard mechanic's capabilities, and even most good shops. Something like the Crane rockers would probably have that pad curvature increased from what is on the 273 lifters, for better contact control at higher lifts, with the compromise of more slippage and side force.... which would be typically be thought of as an OK compromise in a modified engine.