Using 73mm bottom bracket on 68mm shell to increase chainline
I am fixing up an old Diamondback Ascent that has a Sugino GT triple that I would like to keep using. The cup and cone bottom bracket was very pitted and damaged; I don't think it is usable. The spindle is rusty and not in great shape either.
Old BB spindle is asymmetrical and 127mm (40mm driveside + 52mm center + 35 non-driveside). I replaced it with a Shimano UN300 68mm x 127mm BB, because that's the longest they seem to offer. I got the cranks on and there is maaaybe 1mm clearance between the granny ring and chainstay, and the chainline from the middle chainring is around 42mm which is obviously not ideal.
If I use a 73mm x 127mm bb bracket (Sunlite makes one) on my 68mm shell, will that give me a few extra mm clearance and a better chainline? Would I need a spacer? Or can I use a spacer with my current 68mm UN300? Any other options besides an expensive Phil Wood BB?
Thanks in advance,
Miles