I see new sleeves online for this car, but not sure if the cylinder has to be bored out to insert a sleeve, or is there a removable sleeve that can be removed and a new one inserted?
thanks.

I think the block has to be bored out for them. Possibly meant for the repair of one damaged cylinder. Make sure to check this out before ordering. Slight overbore and new oversized pistons are my suspicion once required. Expensive.

Not absolutely sure of this incidentally. A lot of lower 603 blocks out there in good condition with bad heads. Should be able to locate a good one cheap enough if needed.