1964 plymouth valiant with 225/60/15s for the front

Not all A-bodies had those bumper to fender corner braces, I don't think Barracuda's had them even on the '67-69 cars. They were stock on most of the other models, like they were on my Duster and my Darts.

Adding a brace like that might gain you some room, but I think the curvature of the wheel opening bringing the corner back in is probably the biggest issue.

I think the most helpful modification would be something like @mosleyme did to his Barracuda, with taking a small pie-shape out of the bottom of the fender to move the corner in and recontour the opening a bit..

1968 Barracuda Front Fender Modification for 26" Tires

You don't want to use the QA1 adjustable strut rods to push the tire back further as that will take away positive caster from the suspension, which you don't want to lose. And running more negative camber won't effect the clearance at that corner all that much.