For today, the engine is complete. I used a modification of the technique described by Leif here
Radial engines for small scales
of trying to layer the cylinders of the engine. I found a suitable engine, cut out and layered the cylinders, added the pushrods, and then the front of the crankcase. Total of about 7 parts. The pushrods were actually done in one piece.
For those who count, the engine is about 1.25cm, or 1/4 of an inch wide.
It does exactly what it needs to do in 1/144, look like an engine, as most of it will be hidden by the cowl anyway.