milling lathe

I have a 2013 South Bend 8K lathe (Grizzly SB1001), and a friend wants me to mill an aftermarket sight mount to fit his target pistol. I'm not sure what type of attachment or milling vice to get. Does anybody have a recommendation for a lathe milling attachment, either a specific one to get, or...

After reading a few posts on the internet I used an endmill to create a 12mm hole in a 15mm diameter piece of steel. Two flute milling cutter in jacobs chuck in tailstock of lathe. No Problem - easily and quickly done. And yet if I had gone the drilling route ie pilot hole then increasing...