Chuck..
lol thanks maine sail,
for pointing that out as i should have given more info. The spar is deck stepped, There are halyards running as well as wire for anchor /steam light. Dont really know yet if there is a chase or not as this is my first attemp in restoring / upgrading a boat. I was thinking of using a through deck connection " water tight of course" but not real keen on making more hol;es to leak.
Chuck,
The way I would approach this would be to confirm that the anchor light wire can be pulled both up and down in the mast and is free to move.
If it can move I would use it as my messenger to pull a new anchor light wire and the wind data wire through the spar. As you're doing you might want to consider pulling a fresh nylon messenger though as well for future expansion/upgrades.
While you may be able to do this with the spar up it would be easier to do it when down. I have actually installed a radome & bulky cable with the spar up and I definitely don't advise that..


A wind instrument is a PITA to do with it up but a lot more doable than a radome..
I know you probably don't want to run a new anchor light wire but it may make it easier and will give you a new known quality wire for your anchor light. Phil is having a great sale on wire here so that may save you money!