Putting old school 392 in a 70 duster

Well this Is my first " mopar muscle car" build... Me and my dad generally are in the 50's (we have 2 57 plymouths and a 57 imperial ) but I've done pony cars for the competition... And a duster style a body is my dream car to build , and to put a modern HEMI in an A body when you have nothing to start with is from my research and calling every manufacturer of swap parts is a starting price of $10,000 ... Before the much needed body work and other stuff