I’ve some vectors that I’m trying to get on a P7 frame and have the opposite issue as my frame is a 1 inch so the 1 1/8 lower race is too big.
I’m considering having the 1 1/8 bottom piece machined down to 1 inch so it can fit the 1 inch aheadset lower cup. If you did the same you could use a reducer headset?
Or a reducer top cup and your standard 1 1/8 lower. Would be mismatched…
Alternatively for less than a fiver you could try one of these - which may be less of a faff: