My buddy has some plans for the Scratch built 50% Ultimate he built last summer. It is too big of a plane for the engines that are available right now on the market. He put the 3W 200 on it, but for all the problems they have and the little bit of extra power for the extra 4 or 5 lbs that engine weighs than a 150, you would probably be better off getting a plane a 150 will go on. He recently got the Aeroworks 42% Ultimate and it is about 10 lbs lighter with all of his gear installed.

But if you want a big ultimate that is the plane for you. Biggest plane I have ever seen in person.

I would probably go with the Aeroworks 42% though if you care about uplines