so i wanted to toss my own 2 cents in. from front to back. how do you plan on cooling it? if you want 800hp, its going to get a tad on the warm side. running a alum rad is a start, but you would need a custom one, because you will have to put it inside the rad support.
why there? your going to run out of room if your running a roots style 871 blower because the crank pulley will be bigger, then you have to figure out where your going to mount your fans.
as for pans, you will have to do some digging or fab work. i dont know much about v8 swaps in a first gen, so i dont know if you need a rear, front, or duel sump pan.
also, are you running your power steering? you will have to find, or make brackets up for it as well, and if your doing a soa, find a steering box for it.
as everyone else is saying, headers will be a issue, unless you have a wheel barrel full of money to toss at someone to make a set.
valve cover clearance will be a issue as well, unless you put a body lift on it, then you may not have to hack up your heater/ac box as bad.
do you plan on wheeling it? i wouldnt go bird catcher then, that's my opinion however.
you have priced out the block, and stoker kit, but haven't priced a blower, intake, or heads (5 wheel barrels of cash should cover that).
how a bout trans? a T5 will be happy until you lay into it, then after that, you prob wont be able to identify anything so your going to have to get a beefy trans for it. then there's the diff. 8.8's are strong, but not with that amount of power.
not trying to pee on your parade, but these and more issues will sneak up on you, and bite you hard. what ever you plan for a budget, triple it, then you
ll be close. there is a difference on getting that motor/drive line combo in, and getting it in so it lasts.