I remember;
Installing the I beams inside the wing spars. The instructions made sure that no rough contaminate (grit and stuff) entered the spar when sliding the I beam into the opening.
For fear of damaging the aluminum, causing stresses.

If you drill to remove the rivets, there would be so much burr that trying to tap and push the I beams out would be about impossible.

I second the others and suggest the full monty, in bits to save on package size. Would it save on freight ?

If you don't have the instructions and drawings on assembly, you will need them.