Singlespeed chainline adjustment
Could you move the chainring on the crank arm?  I can't tell from your picture if it used to be a double or not? I have an old schwinn that I converted to fixed and had the exact opposite issue (chain line moved away from the bike).  I wanted the 52T large chain ring to stay so I moved it to the inner ring position.  This is probably not ideal, but I've had no issues in 10 years on it.