A repower is not difficult. I did my own except for the lifting out and back in. The yard, Lake Erie, did that with their rack fork lift. Took them all of thirty minutes. It did help that I bought the new Yanmar through them.
I welded up a 'U' bracket to straddle the companionway but still keep the weight centered. Then out came the old 2QM20 with the help of Mark.