Pitotheat gave an excellent reply.
Having done my time as fj pilot and now having seen a fair chunk of long haul widebody I can see absolutely no reason why a nav could not make it. It's a job that requires good levels of SA, systems management, crew co-operation. All of which most navs should have by the time they leave. Pure handling skills, while still important, are becoming less "core" for employers It really does come down to luck and timing. You may have to commit to several years paying off a largish (50-60K) debt with a much lower pay than you left on.
Look at the lifestyle choices, not just now but when you are 50-55, and decide