If your re-powering, I'd say take the extra step and raise it. Only 2 current 25" motors within 50 pounds of the original designs target weight of around 300 lbs. Those are the Zuke 90 at about 345 lbs and the Etec 90 at around 330. Anything bigger is at least 50 lbs more
One view of Mitchmans 20 sinking off Marthas Vineyard is enough for me. Not sure if his buddy's viddy is still on YouTube but 5 inches may have made a difference, i don't know.
Originality is a moot point as there are plenty of these around and safety and resale is better with a properly raised transom. If you choose to keep it at 20" it might be worth looking into the transom well walls that Hermco recently made off of the originals. I think they sold for about 400 clams, but don't quote me on that. They are very nice and very functional. I'm not sure if he has any left or will make more but its worth a look. Someone else recently posted a product from whitecap marine I think, but not the quite the caliber of Hermco's product.
Hermco's contact info can be found at
www.hermco.com
Good luck whichever way you go
