But I do have an engine

Thanks to Tom at Manik (http://www.manikllc.com/index.html), I found a Honda S2000 engine and transmission on Craigslist for a reasonable price.

Looks to have all the bits (except the ECU, which I won't be needing, as Westfield supplies a replacement one) and no obvious leaks, so hopefully it will be fine. I will just need to convince the local authorities that I bought it legally.

It's now sitting at Science of Speed  (http://www.scienceofspeed.com), where they are going over it to make sure everything is OK and it will be fine for track use.