I purchased an assembled Eci 0-360 from Steve at America's Aircraft Engines back in 2005. Steve, Phil, and Steve's dad Richard were a pleasure to deal with. After 325+ hrs the engine is still running strong and I would (and do) highly recommend them to anyone who asks about engine builders.
There are many good engine builders out there, but in my opinion, the real proof of their commitment is when/if you have a problem. I had an issue early on and Steve and Richard did whatever it took to fix it to my satisfaction--they earned my trust.
Cheers,
db