Starting a new project car and need help with parts interchangeability

Thanks for all the info on the front end - that is very good news since it's almost all new parts. On the rear that;s great news about the springs - and I am assuming that the Cuda still has the smaller bolt-pattern rear axles will the duster ones swap over as well? I am not sure about the axle diameter and bearing sizes and whether they interchange or not…

On the header front using the duster power steering box - that I am stuck with no choice at all due to that box? I have read with interest the threads about the spitfire headers and the TTi/ hooker headers and I am guessing that none of these will fit either- what about the fender well headers I saw mentioned back a few threads? I am loathe to cut up the car but if it's my only choice between power steering and no power steering I will be grabbing my hole saw kit pretty quickly….. ( us chubby guys need our A/C and our power steering :-)

What about frame ties- with a mid 400's hp motor will they be needed?

I genuinely appreciate the input guys - this would be my first "A" body project of this vintage and I do remember my painful learning curve on my last project and I am really trying to avoid it this time if i can.