Very Careful
Like I said call Selden,they were very helpful when I called years ago when
adding radar and wind machine on my 290 Hunter.
I also called them recently before I did some drilling into my 36 Hunter and they were very helpful.
I told them what boat and model I had and why I was drilling into the mast,
I was adding a spinnaker bail hook and they told me where my radar cable
and other cables would be and other suggestions.
I new pretty much where things were but wanted to double check before drilling into the mast,you need to be careful when drilling not to hit other cables.
You can look down on the bottom of the mast and see which side cables are,starboard is where most cables are and radar was port but check and see,your port side should be empty and makes easy drilling.
I did my 290 Hunter myself and did take the mast down when adding ST60 wind and radar,it was so much easier than climbing up the mast doing the drilling for the radar mounting and the drilling for the radar cable.
Are you climbing up the mast to do the install.
Nick