The only other thing I would say to do to your set up is either port the stock exhaust manifold or get a good quality aftermarket one. The restriction in the manifolds cylinder 3 port is the main cause of piston and head gasket failures on that set up. Do a compression test to check what your head gasket is like now, if its not low then I would leave it, a good tune is more important. You can set it up pretty well with what you have, should get about 160bhp or there abouts, keep the fluids in good condition and levels right, dont be bouncing it off the limiter or ragging it cold and it should last ok.
If you are going to buy an ECU buy a Jam/Blitz?mines pre programmed type, you will make more power safely from a stock engine, plus you have scope with it to upgrade the turbo to something a bit bigger and it will still run it, without paying for a remap each time you change something. They hold their money as well, you will sell it for the same price you got it in a few years time, I ran a Blitz for years and to be honest, it was trouble free tuning lol.
