I believe he was asking about a block inside the boom for the outhaul, not the reefing line. Other than that, your advice applies quite nicely. I've never seen a reefing line with a block in the boom.
Isomat booms were made with shuttles inside the boom. Two-line reefing system. Was standard on a lot of boats. A lot of people have converted it to single line. The OE shuttles tended to jam.
MiVelero: Does your red line run through the boom - i.e.: does it come out of the boom at the gooseneck ? Are there sheaves there ?