Originally Posted by Aeroplane

Changing the ratio won't keep the crankarm from hitting.

There are bottom-bracket spacers out there. They will work as long as the non-drive side will have enough room to clear when you put it in.

A punch relief is a good idea, but I'd clear it with your shop first. Nothing worse for a bike than a dummy with a hammer.

Safest way is to just get a new, longer BB spindle. But that might throw off chainline. Tread lightly.