I also thought of another inexpensive stand alone engine management solution that comes as a fully assembled ECU: The Greddy Emanage. Now Greddy may not mean much in domestic car circles, but it is a well-established company in Japan for their home market vehicles. Even though it is from a Japanese company, it is configurable for a multitude of different applications and number of cylinders.
Oh, and another wierd idea came to me in a dream last night: A hybrid of an Isuzu Impulse and a Chevy Chevette. They share the same chassis (As does the early Isuzu I-Mark, Holden Gemini, and Vauxhall Chevette), and there was a "Lotus Tuned Suspension" Version of the Impulse. Here is where it gets interesting: there was also a Lotus version of the Chevette in Brittan. So, you could use the suspension and brakes off an Impulse under a Chevette and put a more interesting swap under the hood. Some successful ones that have been done include the Chevy 60 degree V6 and Mazda Rotary. Of course people have also fitted them with V8's, but it is unnecessary and would throw off the weight distribution. You could even put a high output turbo 4 in it from either a Solstice or Japanese Nissan Silvia.