While I have nowhere near the experience of Scott, here are some things to consider:
First off this is a new to you boat and while you did not say, it seems you bought this boat knowing it had one bad motor. That says to me you are both cost conscious and in this for the long haul. That translates in my mind that it’s better to do it right than quick, perhaps yours too. I get that you may be anxious to ‘get boating’ but in the long run I suspect you will kick yourself for not doing it right. Imagine your future-self 3 years from now: will you be happy with always having the throttles at a slightly different setting or will it be an irritation and regret?
Second, you do not mention who is doing the work for an engine swap. If you are trying to tackle the swap yourself vs a rebuild due to concern of skill set, I suggest that the engine rebuild is not that much more difficult. Pulling apart a motor and taking in major sections to a machine shop for them to do the ‘difficult work’ is no harder than swapping an engine IMO. Example > you take in the head as a complete unit and they pull all the valves, machine what is needed, and reassemble it. Here is a vid (
link) I found on a pretty crusty 145 that someone rebuilt. Looks bad to start with but turns out nice.
Third, buying a used engine is a crap shoot. If it’s a rebuilt unit from a reputable dealer, ok but I sense you are looking at used engines. You could end up putting it in only to having to pull it out next season.
Forth, think of the stories you will be able to tell on those outings about how you rebuilt that engine yourself! And if you have young ones at home, well that can turn into a bonding experience.
I think you will be missing out if you do not at least explore doing a rebuild or using the right engine and forget about getting underway next season….