lol great project!

looks like my engine hoist is getting another workout then?you are luucky i had a full car on the last trip(came back here on 28th august0,cos i nearly collected it!

Im absolutley positive standard 3.2 vented rear discs will be ok,as you said engine is defintely lighter and unless your on a track?uprated rear pads will be suffiecient as rears do so little anyway
,bigger pads and calipers on the standard front discs will give you a larger "swept volume" of braking,

but i would go with Woodys suggestion of ML brakes to be honest,as you have them "in stock" makes sense,
front mounted rack would better but nothing wrong with a rear mounted one if it overcomes multiple agro,s by using it,
dont dismiss electric pumps for the power steering bud. many many race cars use these and they are cheaply available and so small you would not believe it!
as you are going auto,diff will be fine power wise but not sure on ratio?guessing twill be fine but stand to be corrected,
biggest tip i can give you is try to use a standard length prop! as its likely to be the only thing,that would keep the car off the road for any great lengh of time if damaged, also makes (usually) the whole business of engine box and positioning a bit easier,it may compromise your ideal position of engine position by an inch or so, but pays off in the long run
