Torch out the hole, and grind away the slag.

Insure the tubing will go thru each hole. If not, retorch it. Grind off the slag.

Lay the cylinder back down, with the 1/8" spacer in, and replace the crossmembers, with their bolts. Place the tubing in the torched holes.

Insure the pin will go thru the tubing and the cylinder. If not, retorch the holes so that it will.