A perfect engine for a Lancair??... well I love YS engines.. sooo
a YS 110 FZ would be awesome on that plane.

It would be a great idea to get it at central hobbies. I just bought one there for $323. Or probably you might want to look for the discontinued YS 91, some dealers still have one... its same weight as the 110.. but If you dont want to overpower the plane..that engine should be great.
Some people would say that is overpowering it.. so also a Saito 91 or 100 would be also great. (But..compared to the YS 110..well.. thats another story

)
I dont like OS 4-stroke engines, Ive had bad experiences with them, a lot of dead stick landings...
Eduardo