Ideas for 60 size engine.
The Morris SudoKoi 60 is the only 60 size Profile I know of.
The kit does not have a good reputation for being easy to build.
If you do decide to go with the SudoKoi 60, there are several people here who have built one. Do a search and you will find the information you need. I believe Wayne Geffon did a thread on his build of the SudoKoi 60.
Or, you try to enlarge a Morris the Knife to a 60 size? That shouldn't be too hard.