OK, fair enough, but like, decades are merely a journalistic convenience, maaaaan.
I just assumed, because no specific year was... um... specified, that 70s would be a Triumph and 60s would be an LPB (you know, like "60s spec" doesn't mean made in the 60s, because manufacturers never started and stopped things exactly on decade turnovers.... boy would that have been convenient).
Anyway, adapter or no you'll enjoy it.
To be clear about the situation - it is in no way dangerous for instrument or amp (a lower Z input is to a higher Z amp is always better as regards that sort of thing - that's why amp inputs are 1M when pickups are usually only 7-18k, mudbuckers excepted of coarse.... but then again, even a mere 30K makes those tube preamps work much harder than they want to).