65er, I have the same front panniers, cept mine are blue. Alright cept for the goofy velcro mounting system, which in theory was and I guess still is, good for bumpy roads so less worry for bags of the era popping off, but getting the second one on properly was always a pain in the keester.
but hey, they work.
My Kuwahara is a 3x7 setup as well. As others stated very well, an 8 speed would be perfectly fine and as Tourist says, a cassette of whatever to 32 (or even 30) is ample, especially with a 24 granny. I used a 50-40-24, so can see how the 42 to 24 is a bit of a jump, I find the 40 to 24 jump a bit much, but still entirely doable, I tend to just pop up two gears at teh back when I go down the granny anyway. If I were do it again, I'd go a 48/36/24 or 26 granny, depending on the rear cassette.
basically, it would be easy to cheaply set up an 8 speed triple setup that would have a reliable, perfectly fine range of gearing for touring on a budget.
Those front panniers have metal hooks and no Velcro... gave them to a friend as I had other front bags.
My Kuwie was originally a 7 speed (freewheel) with a 28/38/48 and had a 14-28 in the rear... the 11-34 8 speed gives wider range and closer steps and I often play with chain ring set ups and currently have a 28/40/50 which gives me a 20-113 gear inch range... find that having the 40 in the middle gives me a pretty good working range of 30-90 gear inches.
When I go back to a 7 speed I might return to a half step / granny set up as I like them a great deal.