Some of my favorite Bills of all time have USFL connections. Levy coached the Chicago Blitz and Joe Cribbs was on the Birmingham Stallions. Dennis Shaw signed with the Blitz after being out of football for 8 years!
Here's all the Bills that were in the USFL, though some of these guys were only replacement players in '87.
C-Kent Hull
G- Ed Fulton, Joe Bock
T- Mike Wilson, Joe Silipo
TE - Dennis Johnson (played RB too, but hey I needed a TE)
WR - Trumaine Johnson, Walter Broughton, Kris Haines, Thad McFadden, John Mistler, Leonard Willis
QB- Jim Kelly, Doug Flutie, Dennis Shaw, Fred Besana, Matt Robinson, Dan Manucci
RB - Joe Cribbs, Terry Miller, Don Calhoun, Arthur Whittington, Ricky Porter, Anthony Steels, Artie Owens, Allan Clark, Leonard Williams
P-Greg Cater, Rick Partridge
NT - Phil Dokes, Ira Albright
DE - Scott Hutchinson, Richard Tharpe
ILB- Merv Krakau, Ray Bentley
OLB - Randy McClanahan, Will Cokeley
S - Dwight Drane, Maurice Tyler, Durwood Roquemore, Larry Friday
CB- Mickey Sutton, Keith Moody, Doug Greene, Mike Holmes, David Martin
K - Scott Norwood, Nick Mike-Mayer, Efren Hererra
KR - Keith Moody
Coach - Marv Levy
Moody is actually an amazing guy. He started raising his siblings at age 19, and set a lot of Bills return records. There's a great article on him here:
http://www.syracuse.com/poliquin/index.ssf/2009/10/keith_moody_takes_his_place_in.html