3SGE breakdown... Going for performance parts. Input? Options

[HistoriCo]

It's been a while since I've posted here, but I've been very busy working etc.

After my car broke down, it will need some repair and I was thinking of buying some aftermarket performance parts for my 3SGE.
I don't have much knowledge about engines overall, so I got a few questions if you don't mind


Since I've been driving without sufficient oil pressure, I was thinking to replace it with the 3SGTE pump but does it fit?
http://www.ebay.com/itm/Toyota-Celica-MR2-...E-/370463114435
(I know I mostly should ignore ebay parts, but just throwing it out here)


Next upgrade should be the camshafts. Not sure how to go with the duration and the lift.
Red somewhere that I shouldn't go any further than 270/270° and 10,5mm lift without upgrading to an aftermarket ecu.
While upgrading the cams I need to do the valves, valve springs and valve seals as well. Can I use parts that are made for the GTE model?

Stainless steel exhaust manifold: Found this part at fensport http://www.fensport.co.uk/Parts/Model_14/Category_4/3413
Will it make any difference from the stock one?

Same question with forged pistons (found here: http://realstreetperformance.com/store/cp-...-2-0l-269.html)
As an NA engine it has higher compression ratio than the GTE engine, but the link says it fits for both 3SGE and 3SGTE, so I'm kinda lost here.

Any input will be much appreciated!

-Simon

This post has been edited by HistoriCo: Sep 2, 2013 - 1:10 PM