Main Halyard and antenna

Picked up my new main halyard yesterday, 90 ft of Sta-set, new head fitting also. Install tomorrow and go sailing. Another issue, my masthead vhf antenna is kaput, and I bought one to install on the pushpit rail, but the fittings on both ends are 5/8th. I don't want to put a hole that big in the combing just to pass the cable through. How do I manage this?David Dobbs, CAL29 411