Aftermarket frame rails?

no OEM brackets....you could add the A body one piece upper shock mount / UCA brackets that Classic Industries offer....or morph B/E body assemblies available from AMD onto the rails. In my opinion, they are targeted for custom builds, not OEM replacement.

this one is getting a 04 Mustang II strut front.

View attachment 1716051858
is the bend/"kick-up" the same inch wise as a factory frame rail? front one that is.