I like the idea of a 10k RPM 4AGE engine in a Caterham, or a nissan CA18DET. But i think I like those engines because I am nostalgic of my "tuner" days. I don't think I would want the headache associated with ordering repair parts from Japan. My stress free engine set up would be an engine that had parts readily available at the local dealer and modern engineering for trouble free operation and performance.
if you google 4AGE seven you should find a pretty blue car from NZ, it might even link back to this site (I cant remember).