Bobbins are the most common type, the best might be metal class 66, slightly curved sides, but you can use plastic Apollo (aka 66) if you happen to have another machine taking this bobbin type.
I have never seen a 1930s or older machine with original wiring in good conditon, it can be shockingly bad, twisted or two core woven outer insulation; the woven part can be fine, but the inner rubber part is often stiff and crumbling to bits. Some 1950s and 60s machines can be in good condition but it has to be checked.