While Burns is under rated and I have little to go on in judging Sullivan I would pick the Boston strong boy. Sullivans size and dominence within the division suggest that he would be too much for Burns.
I would also favour the "Boston Strong Boy", but IMO Burns quick and unpredictable combinations in the infight would do a lot of damage and would let Burns be well ahead on points, until Sullivan lands something heavy and KO´s Tommy, who´s really very underrated (especially as a p4p- fighter)... Sullivan TKO 10 Burns