Show Your Big Block A body!

What has a 72 demon and a 66 barracuda have in comon a demon has more room so I don't know how that can help me please can someone help out us so my kid can do this he's about to give up all we here is eather he can do it or it can be done what I need to know is OK I need to know what parts headers motormounts radiator throttle linkage etc etc