Frame rail replacement help

Do you have the factory Chassis Manual with the dimensions? That and a friend with an A body to measure against. Best of luck man, I admire the dedication. The repo stuff is sometimes slightly different from factory, so measure twice, then again.

Can the outer rockers stay together as a reference? Keep any good factory metal and trim the AMD stuff as needed.
Yes we have the manual and we have a neighbor with an abody rust free on a rotisserie that we can measure too. Outer rockers are good.