This post somewhat confuses me, if I understand correctly, you have a 6" stud wall that you originally were sitting on a wide flange beam, you were worried about the beam width being narrower than the track supporting the studs. Then you changed to an HSS beam and have a connection detail consisting of a beam seat.
Based on the information I can gather from this post, the beam is acting as a lateral header type member, in which case I would rarely if ever use a wide flange beam as they suck for weak axis bending without bracing, not to mention torsion you would be placing on the wide flange. An HSS would be your best option. If we are truly talking about about a header type scenario, I would make the header the same width as the steel studs to better control horizontal deflection (weak axis of the HSS from I presume wind loading). For the connection to the column, assuming the column is really a jamb stud column, I would directly weld to a sim width column and call it a day, I don't see a reason to provide a seat and angle as you show, unless the loads are such that you need additional capacity of the connection because the beam is less wide than the column and the column web is too thin?