is 11.2:1 compression too much for 91 Octane

1970Duster said
A 458 Italia runs 13.5 to 1 compression and does it just fine on pump gas. Just sayin

I have no idea what that is or how modern.

Off the cuff I'd say no except the cam is a unknown. If the cam is really large in duration, hou may, may get away with it. You may, may have to find yourself a very thick head gasket to run at a slight less compression ratio.