Use the Neo head. Better in every way - it will not have too high compression. I have stock pistons with Rb25 head and only 132psi per cylinder. Even with higher compression pistons the Neo head will not be too much.
I bought some cheap 17 x 8.5 in rims for the track (M's - never heard of them) and they were chrome finish so I painted them black (with a brush - heavy duty paint!)!
If you think you might prefer a manual definitely buy a manual - the conversion is straightforward but pointless if you know you want a manual - best look out for one. Auto is great for city traffic and towing but not so good at higher power levels and no fun on the track.
You won't need a new ecu - on the other hand you will have a greater choice of aftermarket ecus if you want one.
Get a GTR box they are fairly cheap. Here's how on a Stagea - it will be much the same I'm picking:
http://www.skylinesaustralia.com/forums/topic/125047-stagea-manual-conversion-guide/
Impressively simple! Did you use existing bolts or did you have to drill and tap them? What ecu are you using it with? Where does one obtain a GT101 sensor?
Already told you 35/40 was too big.
A Link is an ecu that runs a MAP sensor instead of an AFM so not bothered by atmospheric BOVs.
Do some more reading before you spend more money on unsuitable gear.
Forget the atmospheric bov for now (until you get a Link)
Don't just ask people to tell you what to do - spend some time reading this forum - especially the RB25 turbo upgrade thread and then ask questions if you get stuck.
ECU options include Nistune - (better than an E-Manage assuming you have a manual) but do some reading on how to acheive this on an R33 - or Link (and myriad others)
A Garret 35/40 would be a crazy turbo for 300kw (400hp)...again read the rb25det turbo upgrade thread.
Most stainless highmounts are cheap and nasty and break. Read below for budget alternatives to a 6boost but your stock manifold will be fine up to 300kw.
People seem prepared to spend in inordinate amount of time and money trying to better the stock fan set up - seldom successfully and often the result is chronic overheating! Not saying it can't be done (I'm sure Dale's will be perfect) but at the end of the exercise your car doesn't go any faster or handle or stop any better!! Still on stock radiator and fan myself - no overheating at track as yet (but with the next power increase going to fit the oil cooler I have standing by).
If you can get some recommendations for a good cam grinder in your area (or anywhere really) he should be able to make a cam to suit your requirements (not just 500kw but street, track, drag or a combination) for a better price than HKS etc.
I had the basic version of the SAFC on my RB25DET and don't know what the SAFC2 looks like but it should be obvious how to set it to zero which is where you would start. Select the car type and sensor type (hot wire) and set it to zero.
NZ Pretty much bang on in AU $$Freight was quoted at NZ$68 so total NZ$248 or about AU$200
For those who don't know it is not just a bolt up job - there is some drilling and grinding and tapping etc required and you will need an extended oil pick-up.
It would help to know how much money you want to spend over what period of time and if you have a power goal but some very basics:
1. 3in turbo back exhaust.
2. High flow panel filter for your airbox (supposing you still have the stock airbox).
3. Bypass the boost solenoid and get a cheap boost T (or an expensive electronic boost controller if your'e so inclined) and run about 10psi.
4. Heavy duty sway bar (anti-roll bar) for the rear e.g. Whiteline BNR11 XX 24mm) which will dramatically improve cornering.
5. Plan to get a brand new fuel pump.
Check to see if your auto fluid has been replaced (ever) and think about getting a S2 or aftermarket trans cooler. Replace your brake fluid with something like Motul RBF600. Check your rotors and if ok get some quality pads next time.
Have a look around this forum for lots more ideas of how to lighten your wallet and make your car better! Read the RB25DET turbo upgrade in the forced induction section for examples of mods and what they have acheived.
I believe the front diff can be changed without pulling the engine but haven't done it myself.
I think the GTS4 had 4.3 diffs. All R32 and 33 GTR diffs are 4.1
Sorry not much help but sounds like possibly ignition switch problem. I presume you have tried tightening the battery terminals and or jumper lead from another car?