The engines you list are good ones. But I'm curious why you leave us with the impression that the OS 120FS would not be a good choice. My Venus II started life with a Saito 125 and after 20 flights I was so disappointed I pulled it and installed my OS 120FS. I got 500 MORE rpm's on less fuel with the OS. I also have a YS 1.10 in another plane and the OS will turn within 200 rpm's of the 1.10.

I've been flying my Venus II / OS 120FS for over 300 flights and the OS 120FS is an excellent choice.