Jackson, early. Far better technique, and skills. His shots would land first, and Mugabi wouldn't handle them at all. Basically, I think it'd be similar to Jackson-Drayton. Jackson KO 3.
I kinda like Mugabi to land a counter and win early. The only thing I'd bet a penny on is the 'Under 6.5' though.
I don't see it as a pick em at all. Mugabi is certainly live, but Jackson should be considered the solid favorite here. He was just a better fighter, with better skills, who beat MUCH better fighters than anyone Mugabi beat. Yes, Mugabi took a helluva beating from Hagler before going down. But in terms of power, you can't compare Hagler and Jackson. Mugabi never met a punch he could avoid. In all likelyhood, he gets destroyed. Bear in mind, Jackson was also a good 3 inches taller than Mugabi, and checking Julian's resume, he never really lost a smaller or shorter guy.