Unlike a main or a headsail where the dimensions are fairly critical for good fit and performance, there's more leeway for fit with spinnakers, esp cruising spinns.
In this case I'd consider an on-line loft like FX sails - they can ship anywhere in the world and generally have about the same delivery time as local sailmakers. Google them and get an estimate.. their prices are very competitive compared to brand name locals.
1984 Fast/Nicholson 345 "FastForward"
".. 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)