if it was me doing the ecu, id just put a pfc or get trent to do a full emu setup..
run a T78 or a T88 turbo if you like trust.. if not a T51R or T04z, a mate of mine ran 11.3 @ 133mph in a 33 4 door and semi slicks, so he spun them hard.
you can use the box, but you can always sell it up and use a GTST or GTT box with a dog engagement set
100mm thick cooler is good for your plans, never said it wasnt good.
Fuel system MUST be there, so if i was doing this i would do it big.. 2x external pumps and surge tank, 800 - 1000cc injectors.
if your going to run a big power engine and be reliable, then a full set of forged pistons and eagle steel rods or whatever else you can get. While the engine is apart, get your tuner or engine builder to put a decent set of cams in.. you can even speak to URAS or the boys at CREATD on piecing together good engines, they really know their stuff.
You can run full power in 3rd gear, but make sure you select them clean otherwise you will smash syncros etc with big power.
Also with a good clutch package, your going to be running a decent slick so i would say put a Tripple plate clutch in because you want it to last more than a couple of outings yes? might be a bitch on the street but its what happens when you build a tough car.
A Two way LSD diff would be good, for a clean and straight launch.
If you want to know anything about jap stuff to build a killer engine package speak to Trent (URAS) hese very very good with this sort of stuff..