If the 123 is always a number, then you could try an action of the type "Replace with regular expression for TITLE:
Search string: (\d+)
Replace string: $1 -
actually it's a mix of numbers and letters like this 1m01b, and that is not always the same but is always made of mix of letters and numbers with space at the end, thats why i thought of focusing on first occurance of space (if that is possible)...
I think you need a space right before the last bracket (for some reason this did not translate into the post when I copied and pasted it ...) $regexp(%title%,(.*?)( .*) ,$1 -$2_)
the _ indicating the space character