Here are some pictures of the latch mechanisms for the 73/74 seat.

They are different than the earlier 70/71/72 E and B body seats.

The 73/74 E-body seats had steel pins sticking out of the sides of the bottom half. When upright the upper seat hing arm rested against the steel pins. The latch was attached to the inside of the hinge arm and hooked the steel pins on the base to latch the seat.

From the pictures I can find it appears that the latch should just swap sides EXCEPT I think there is a motion limiting tab on the latch that would be left/right specific. If it is, then it is an easy fix to bend/modify it.

Unfortunately I do not have my 73 & 74 E Bodies at my house so I can't get up close and personal with them but if you need me to I think I can go over to get some information from them in the next few days.

Since the steel pins and hinges seem to be identical side to side I think you can swap the latch with little to no effort.