So I picked up an 8 speed groupset recently, mostly Athena with a little Chorus and some Mavic wheels. I was reading up on it before it arrived and as far as I could tell (Velobase and other sources) it was going to come with a 111mm bottom bracket. Well it did, but it's a Shimano UN-54 - JIS taper.

So where I'm at now is wondering should I stick with this BB? From what I understand the Athena cranks (which I'm fairly sure these are - I know the Campy designs filtered through their groupsets during the years - these have an A3 date code) were designed for a Campagnolo tapered 111mm BB and that this JIS tapered BB should put them slightly further out - not as far as ISO cranks on a JIS BB but a little nonetheless.

Is the difference and hence the performance going to be enough that it's worth springing for an old early 90s Chorus BB or similar (about 60eur around these parts) or is this something I shouldn't worry too much about and simply mount them again as is?