It is not a common job to do. The plane is pretty small, and the hatches are not real big or convenient for all the installation. Much fuel may need to be external.

I think 9-14 pounds thrust is acceptable for the airframe. (Most bigger engines will make the gross weight very high when you factor in fuel and stuff.) Will be much more manageable if kept light.
I have flown Ultra-Vipers, and Mavericks with this thrust range.
As far as installation... I think it would be a do it yourself. Not reccomended for folks without relavent experience.

Have fun,
David