Is the clip meant to close the chain for service use or as a facility for rolling in the new chain, then peen the link to close it permanently? If you check the Buy Parts link (no pun intended) at the top of the page, you'll see that a peen type link is available separately from the chain.

You might as well button up the engine with the existing chain and check elongation. If necessary, you can roll in a new chain without taking the engine apart. Only the valve cover has to come off.

Sixto
87 300D