You wont find that little block on many racing BRs. With a properly made hole through the yard it is not required, and rather a problem.
I agree Claus. It might surprise some people to read that I made a hole through Gladys's yard to secure the halyard. The benefits are to secure the yard closer to the mast and avoid disconnecting the halyard from the yard when reefing - a bad time to accidentally let the halyard go and watch it disappear out of reach! I secure the halyard to the reefing positions on the yard using soft shackles (thank you for this idea Graham). These have never failed in use, although slightly fiddly to use.
I've not previously advocated drilling holes in spars on this forum because it is imperative that the hole, as Claus says, "is properly made". Simply drilling through the hollow spar at a point of maximum stress with a tube-collapsing halyard under tension, and unsealed from water could cause problems. On Gladys I was careful to install a small supporting tube internally through the spar to counter the collapsing force and to seal it against water entering the spar. I then reinforced the spar with carbon tape and epoxy wrapped 100mm around the outside of the yard or so on either side of the hole.
Incidentally, I also epoxied carbon tape to the leading edge (tension side) of the wind-surfer derived yard to stiffen it. I justified the slight weight increase of carbon reinforcement by offsetting it against the weight reduction gained from using a smaller (6mm or 8mm) diameter and stiffer Dyneema halyard.
I think these mods, amongst others, made a material difference to Gladys's satisfying racing performance, including against Bermudan rigged versions. And I never obsessed unduly about mast rake, just eyeballed it to match the mizzen - more a cosmetic consideration than technical!
Claus also makes a good point about protecting the sail and spar when transporting the boat on a trailer. Soon after buying Gladys I had a bespoke sail and mast bag made of mediumweight awning material that contains all the masts, spars and sails in one long bag. The bag protects them from road dirt, UV and minimises the number of potentially damaging ropes and ties needed to hold them together. And being gunter-rigged it is not necessary to dismount the mast from its tabernacle.
Matthew
BR20 Gladys (sadly now for sale)