The early and mid '80s Islander Bahama setup is just the clue line portion of the two line slab reefing system. The tack reefing line is replaced by the reefing hook on the gooseneck.
Don't bend the clue reefing line onto the reefing cringle at the leech of the sail. That would only provide a 1:1 mechanical advantage and you would have a very difficult time getting the reefed foot properly tight. Instead, locate a padeye on the side of the boom, slightly aft of that reef point. Bend the reefing line onto it, run it through the cringle, then into the shiv at the aft end of the boom and out the shiv near the goose neck by the cam lock. That setup gives you a 2:1 mechanical advantage. This diagram
illustrates how the clue line should run -- note the dotted line where the line runs from padeye up the far side of the sail to and through the cringle, then down to the boom in the left-hand diagram of the system 1 illustration. Yours will run to the end of the boom instead of to a turning block.
The reefing point in the luff should hook over that ram's horn reefing hook on the goose neck. It will look something like these
do. In fact, mine is the K-10501. Point B in the inset of the right hand diagram for system 1 in the aforementioned URL is pretty close to our system.
Your mainsail should have two reefs. Conveniently, the Kenyon boom can handle two reef lines. You'll note there are two shiv paths in the boom and a cam lock on each side of the boom at the goose neck.
I have found leaving sail ties in the first line of reefing points all the time gratly speeds up reefing. It may not be pretty, but I don't want to stand on the cabin top any longer than I have to when the wind is freshening and we are bouncing around.
There have been lots of reefing discussions here on Sailnet over the years, and they are worth reading. Use Google to find them with a query like "site:sailnet.com reefing" but without the quotes, of course.