Generally if the rope will pass through you'll be OK... in rare instances the sheave is wire dimensioned only... but if you currently have wire/rope splices and the rope passes through you should be fine.
Look for a low stretch line, (several makes available) expect to pay $2/ft or more for the good stuff....
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)
1984 Fast/Nicholson 345 "FastForward"