Hi y'all. I have an '81 Schwinn World Tourist, made in Taiwan by Giant. I'm replacing everything on it. I can't seem to find any info on the web about whether it uses an ISO or JIS headset. I don't have much money, so I don't want to order the wrong thing. So, does anybody know which I should get - 26.4 or 27 - for the crown race inside diameter? It's pretty stuck in there, and I don't really want to remove it right now to measure because I don't know how accurately I could measure it anyway.. plus I'm riding the bike currently, as it's my only one.

Also, I've decided I'm ordering a 26mm seatpost for it, and a 68mm JIS BB. The original seatpost wasn't present, and the replacement one that it came with was a tight fit but no size marked. I measured as many things as I could and did lots of research. The bike originally had an internally geared 3-speed hub, and a 122mm JIS BB spindle. im ordering a wheelset with a 1-speed Shimano coaster brake hub, and a JIS crankset. I know I might have to try out a couple different spindles to get the chainline right, but with the similar hubs and cranksets, should I just go with a 122 again? I'm wondering if I should try a smaller spindle in hopes of getting it right the first time. I know the bottom bracket spindle length/chainline question is almost impossible to answer, I just figured I'd ask in case someone has done this before.

Does anyone else have one of these frames? I don't want to order the wrong headset. And if anyone does own one and has ANY info they can provide on it and it's specifications, that'd be great.

Thanks