OK, so you are basically proposing keeping the ST60 and upgrading everything else, and hopefully reusing the thru-hull.
I replaced all the "electronics" in 1974 boat and could not be happier with the result. I installed an NEMA 2K bus and was impressed with the level of compatibility between the brands.
I used a Maretron DST800 for depth/speed/temp, but the Raymarine
version I found out later would have been much cheaper (<$200 from Hodges Marine). You will need poke around to see if the thru-hull is compatible with the nexus version.
For wind speed and direction I used the the LCJ Capteurs CV7. The thing about CV7 if if you have 4 wires coming down the mast
from the old system, you can just splice in if don't want to run a new wire since it's good old RS-232. That keeps you from having to run the N2K bus up the mast
. A quick review below.
Then you just need to get a small Raymarine for display of the wind info. RM makes a dedicated wind display or just get a RM small chartplotter
, which would be simple to connect to the seatalk
Even though I have 3 brands of instruments talking on N2K bus, they just work