lookin for sum insight on 4 6 drop

[lamchop]

was thinkin on droppin my truck (66 shorty fleet) can get 3 5 or 4 6 drop kit for same price. comes with springs,shocks, shock relocators, adj track bar. pretty much everything except c notch.....(which i hear conflicting stories as to whether its necessary or not)?? is a 4 6 kit too much? will springs /shocks,etc...be all i need? never dropped a truck before. is an alignment neccesary after install? any other concerns i should be aware of? i appreciate any help or guidance. thanks fellers!