There are some BB without a shoulder to seat against, like, Phil wood ..

its not like Shimano's square taper types,
they would have a shoulder to tighten against.
Budget suggests a square taper , and a 110 bcd crankset,
to use 34 and larger chainrings.

if using an external BB of new stuff, it may not be critical

never owned one , maybe 2 _1mm shim spacers 1 for each side,
rather than 1_ 2mm
on the right. get all 3 and see..