upper shock mount fitment issues with turbos

I have a 65 dart that iam looking for some help with, i was going to use magnum manifolds and they will fit with very little effort but i found a set of headers on a truck in my salvage yard off a magnum everything is in the same location but the tubes stick out alot further and wont fit because it hits right where the uppershock mount is.

Do any of you have any ideas on what i could do to make these fit i was thinking of cutting out the inner fenders but it sounds like i would need to a cage can i get away with just tieing the front to the firewall any ideas ???? Iam not opposed to putting in a cage just wanting to get this going and tuned with as very little cosmetic work as possible