If the question is just to do the delivery, then do a repower, I would say go for it in most instances. If there is an area that you will definitely need an engine because of something like current, then think twice but if it is a relatively easy sail, do the delivery.
There are a few options for getting limited propulsion. One is using an inflatable as a yawl boat. I think that a lot of people would be shocked that all but 3 of the Maine windjammers have no inboard engines and use yawl boats and they are operating commercially. The other option would be to mount an outboard bracket on the stern and use that for the delivery.
For a permanent fix, neither of those two options are ideal unless you are a purist and don't want an engine. I suspect that you would really miss the inboard quickly if you went engineless. There is also the cost of the repower to consider.