Get youself a copy of the factory service manual!

There's a sequence for removing the cam towers which cover some head bolts. Get it wrong and you'll have a two-piece cam. The 126 FSM on CD has verbiage and diagram which contradict. The verbiage is correct, the color of the arrows in the diagram is wrong. The 124 FSM has it correct. But get an FSM anyway

Aside from the 2 small bolts into the front cover NJ300sdl mentioned, there's a bolt off by the fuel filter.

Set the crank to #1 TDC. Don't worry about the IP but don't touch it either. Index the chain to the cam sprocket, remove the cam sprocket (IIRC there's a semi circular thrust bearing to watch out for), remove the tensioner, remove the upper chain guide. Don't worry about the chain. It can only fall so far into the front cover and won't come off anything else. You can retrieve it with a hook or magnet.

For removing the upper chain guide, this tool is worth the price -

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=370249177688

There is a pin in the head and a pin in the block. The pin in the head will be covered by the upper belt idler if your engine has such a beast. Note how the upper chain guide is installed. One of the holes the pin goes through is round, the other is elongated. It fits either way but I don't remember which way is right. The FSM drawing vaguely shows one more elongated than the other.

Sixto
87 300D