You might be able to put a 429 in a Falcon but you'd probably have to spread the shock towers apart, with a unibody I woulden't put 500 hp in it ( It would requrie a tube frame ) and also, if it was a 6cyl Falcon, it would have a weak 4 lug 8" rear, so, as much as I like Falcons ( Cause I own 1, of course ), I'd have to lead you to using a Galaxie/ Fairlaine/ Torino because they are framed cars and it would be easier and safer.