Specifically looking at a Triumph Bonneville, T120 around the year of my birth 1963 General and bike specific advise welcome
Everyone should have a Bonnie at some point, and I really enjoyed mine. It was a full on hobby just keeping it shiny much less running well! Not so sure about a suicide gearbox though on the sixties bikes. Mine was a low miles '78. Hope you find what you're looking for.
I am on a similar mission to find the 1970s Mk III I rebuilt as a youth…… nostalgia gets worse with age