i recommend you use the "carb" & intake currently on your crown vic, then all you need to do is change the firing order to 1-3-7-2-6-5-4-8. its an easy swap that will give you an extra 30-40hp and every thing else (including your AOD kick down linkage) will work.
the 87 0-2 sensor will recurve the fuel/air mixture to accomidate the H.O. motor.
in my oppinion the cost / Trouble of converting to multiport EFI isnt worth it for the few extra horses.
i wrecked my "rare" 86 grand grand marquis 2dr so i know how you feel about your car.
ADDITIONAL DETAILS :
you dont say what year/ model H.O. motor you intend to use so all i can tell you is :
if the induction system is the same your harness will plug right in
if not you will have to use your current induction system.
i thought the 87 crown vic only came with CFI induction AKA throttle body injection (looks like a 2bbl carb)
i didnt know multiport EFI was an option (on the 87 crown vic)
BUT IT IS a rare coup and likely custom ordered.
P.S. i just read http://answers.yahoo.com/question/in...5032837AAG6ur1
and i am gonna tell you i like the 5.Oh plan but i think all your 87 302 needs is a new timing chain & gears. $25 parts.