Topic: Boom and spreader dimensions
Depending on the vintage of the spar, you can source parts from South Shore Marine (think thats the name), out of the Toronto area I believe. They were all Cinkel spars, with the newer ones having a diamond cross section and "wing" spreaders. The earlier spars had oval cross section booms and masts, and the spreaders were nothing more than some aluminium tube with spreader ends riveted on. Check out boatforsale.org and look in the parts. I'm sure you can find something used.
Looking now at your post and seeing hull 334, you're going to have a harder time making your own, as you'll have the newer Cinkel mast. Have to get someone with a newer boat to get you dimensions... Mine's old... Cheers