That second one is excellent. My understanding was that the vents are on the sides to accommodate the sporran strap...doesn't seem like that practical of a consideration but that's what I heard.

Best of luck with the conversion. I would suggest that when you decide just how much to shorten it that you do it with your kilt and the jacket on you and have someone help you mark it...sometimes jackets just seem too short and I think that it's a question of matching the proportions to your own build

Best

AA