Franchi,
The conversion of the ASP .46 to diesel is not a good idea.
Three years ago I did just that and the crank had failed at the inlet port in such a way as to make it's removal (either way) impossible without gouging the case bearing.
The rod was bent, and the piston broken, and a deep gouge had been formed in the liner inner wall.
The engine seized while the plane was flying and I had a diesel mixture of 1/3 - 1/3 - 1/3 diesel fuel mix.
Here is the link to the engine review:
Sceptre Flight
The head was made by Davis Diesel Development which has gone out of business.
Here is a website to show you how to make your own?
Make Your Own Diesel Conversion Head
Personally, I would buy an engine designed to run as a diesel engine.
I have run many converted glow to diesel engines and they don't last as long as a diesel designed engine.
I've tried converted Cox engines (contra piston failure), Irvine 20 and 40 ABC engines (con rods wore out and failed), (one) OS 4-stroke engine (Knocking like an old diesel truck)
and turned it back to a "glow" engine before I wrecked that engine, and tried some Davis Diesel head conversions on other motors.
Good luck!
sosam117