I don't think your transmission will fail you. I bought my first 84 fj1100 with 47,000 miles on it. 2nd gear would pop out only under hard acceleration around 8500 rpm . Over the next 26,000 miles of aggressive riding it progressed to popping out at 6500 rpm in both 2nd and 3rd gear.
I finally broke down and bought a transmission with undercut gears from RPM and installed it . I inspected the old transmission and other than the worn dogs causing the jumping out problem the old transmission looked fine .
Thank you; your real world experience is very useful. I am planning to fix the issue and have chatted with Randy via email; however I don't have enough time to do anything about it before the trip.