I feel like this may be a bit far fetched, but as I was going through young white male UIDs from the late 70s I ran across the 6 still unidentified John Wayne Gacy victims. Several of his victims were picked up at the main Chicago bus station, and evidently Brian was last seen after being dropped off by his mother at Houston's bus station. Known non-Chicago area victims were from other locations in the midwest like Minneapolis, Omaha, and Kalamazoo. None of those identified have been from as far away as Texas, but that might be a key factor as to why they went unidentified in the first place. Most of those still unidentified were killed sometime between summer 1976 and summer 1977. That time period fits nicely if we are to assume Brain drifted around the country "to find himself" following his withdrawal from classes on March 9th, 1976 and knowing there was no activity on his Social Security number after 1976.
Unidentified Victims of John Wayne Gacy
Victim 28 -
954UMIL is definitely not Brain due to being killed before July 31st, 1975.
Victim 26 -
956UMIL doesn't seem likely due to missing the two upper front teeth and being 5'4". Likely killed between June 13th, 1976 and August 6th, 1976.
That leaves:
Victim 5 -
958UMIL doesn't seem to be the most likely due to having a key fob with the name "Greg" on it and being estimated as 22-32 years old. Likely killed between January 20th, 1976 and March 15th, 1977.
Victim 10's -
957UMIL reconstructions clearly show a broad facial structure, which doesn't seem to fit Brian. But, that's only my non-expert opinion. Possibly (listed as low confidence at the Cook County SO link) killed between March 15th, 1977 and July 5th, 1977.
Victim 13-
955UMIL Likely killed between August 6th, 1976 and October 5th, 1976
Victim 21-
962UMIL Likely killed between August 6th, 1976 and October 25th, 1976
