Rear engine crossmember removal

[Captmatt]

Getting ready to install a auto trans behind my L6 motor. Trying to decide the best way to remove the rear engine/bellhousing crossmember. I would like to remove without damaging it. I don't have a lift so I will be working on my back with limited access and the motor in place. Looks like some of the rivets are going to be difficult to get at. Any suggestions from people who have accomplished the removal with out damage ? Should I just cut it out ? I don't mind a little extra work to save a 50 year old part if I can.

Any suggestions welcomed, thanks