[dsraven]

you can use the cleco rivets between the parts if you drill a spot so the cleco's will fit between the two parts but still leave the right space for the weld. the cleco's themselves are too thick to rely on their gap to be right so if you simply make a wide spot where the cleco's go you should be fine as long as the gap between the parts is still about the same as your mig wire thickness along the remaining length of the gap. use a flat washer behind the 2 parts for the cleco to bite on and keep things lined up.