need help

Hello to all
this is my 1st time in a forum.
i own a 97corolla that has a 3sgte swap (swap was done prior to my purchase of the car).The tranny i beleive is from a camry.It has a air to air intercooler.I know the engine is a 2nd gen 3sgte but when the swap was done the engine was fitted with a airflow meter and was wired to a 1st gen ecu (engine didn't come with harness or ecu).
i need to know from a performance stand point if i should put in a 2nd gen ecu with a mass air flow sensor.
i also heard that #3 cylinder can run lean because of a flaw in the intake maniflod design.What would be the best solution which represents a compromise(50/50) between cost and performance.
i have been told that a turbo from a 3rd gen supra(single turbo inline6) would be a good upgrade from my stock turbo as it is very efficient up to 19psi.Is that true?
Space is very very limited in my engine compartment so options in turbo upgrade and manifold design are limited. what would you suggest as an upgrade(looking to make around 280 to 300hp at the flywheel).
Any other suggestions in terms of reasonable upgrades to reach the 300hp level are very welcome!!!