440 vs 360 GO!

with aluminum heads the big block will be about the same. $1500+
cheapest way to install is with schumacher mods + schumacher headers

luxury method is hemidenny kit + front disk kit.

you will need to fresh up that big block trans too. what rear is in the van? might be a dana but that will cost some bucks to retrofit for ABody

also 440 is a tad bigger than 383/400 height-wise. so you will want an offset master cylinder and some even put a smaller heater blower motor (some use a rear defroster motor) otherwise you cant get the valve cover off without droppin the heater box