What Jim said. Ideally the lock tool is attached to the IP and the crank is at 14*ATDC #1. If that's not the case, pull the IP with the crank at 14* ATDC #1 or whatever position you want for base IP timing. Don't rotate the crank while the IP is out. Put a bar through a hole in the cam sprocket to hold the chain while you loosen the bolt through the IP timer. It's a right-hand thread as Jim said. The chain won't slip off the timer and the timer has nowhere to go so don't be concerned with letting it hang in place while the IP is out. If you're not convinced, hopefully your engine has a basket behind the vacuum pump that will hold the timer in place. If not, folks with 603.96 parts should have a basket to lend you. I might have one. Or zip tie the chain to the timer through the center hole left when you remove the IP. You might scribe timing marks between the IP shaft and timer but the spline is so fine that it'll be an eye test later. Better to resign yourself to checking and adjusting IP timing when you install the IP. Go to the tools forum and borrow an A-B timing light.

Sixto
87 300D^2