Well from one anal retentive nerd to another, you'll never be happy with how the engine runs unless you do it yourself, so I'd recommend diving into this with both feet.
TwEECers software works fine. Is it perfect, no. Is it wonderfully documented, no. Does it work, yes. Is it free of major bugs, yes. Diablo and SCT have offerings too; both of which are better documented, more complete, and more costly. The functionality they uncover can be useful, but to be completely honest Tweecer exposes everything you need to make the car run great. Let's put it this way, I'm using really ancient Autologic software that predates Tweecer, and even that exposes enough functionality for me to be happy with all my EEC-IV vehicles.
If you want to get a feeling for what kind of parameters are available and what the software looks like you can download it in advance. You can also download paul booths software, which
www.moates.net devices works with. You could do this with the moates stuff too; it's just slower because it's not USB and flashable in-car, as far as I know. Anyway, I'd look at the software before you buy...and keep in mind, you will be starting with the Ford template and Ford parameters...so change nothing and it runs like it does now. You will start small...change engine displacement to actual, raise idle rpm 300 rpm to make sure it works...try it...repeat...