well you should worry about a compatable ECU...a P28 or a P72 with crome is a LOT cheaper than any standalone system, and if you get a piggyback (VAFC/E-manage) i will come track you down and beat the ever living shit outa you (unless you live in dallas...in that case, just give me a call when your new engine explodes...ill build ya a new one).
Id recommend getting a P72, crome pro (spend a lil extra cash to get the ease of real time datalogging) setting up a base map, street tuning it, and then taking it to get dyno tuned ASAP.
If youve got an H23 you might as well keep it the way it is and build up from there. The H23 head has a unique quality...its extremely similar to a 4g63 head in exhaust design (meaning you can steal a turbo manifold from an eclipse gst/x or a talon tsi), and that similarity will save you a bit of cash. Also with the H23, you can basically take an entire eclipse turbo setup (dont forget the injectors), replace charge piping and get a FMIC. Call it a done build. Good luck.