Are you sure you did not already process this trade:
http://www.predsff.com/forums/showthread.php?t=21500
MFL shows John at 67 years, with 2 on IR, so legal at 65
As to the minimums:
Beginning with the 1st day of In-Season Free Agency, each team must maintain a minimum of 13 Offensive Players (IOP's) and 9 Defensive Players (IDP's) on their Active Roster. The 13 IOP and 9 IDP's can be any mix of positions within either side of the ball, as long as you have at least 13 on offense and 9 on defense. During the off-season(which commences after the Super Bowl, teams are allowed to be below these minimums.