Well define too much... Many have flown successfully with the extra weight of a conventional 120 and you could argue that you can't have too much power. However, I would say it is a bit ott for the Swallow.

The YS 91 really would be ok on 20% nitro, more than enough on 30% and the 110 shouldn't be more than a few bucks more than the 91. If you can wait until June then it is the one to go for, if not get the 91, it will fly much better with the lower weight over the 140 and you really won't be lacking power.