Well, you may get lucky and not have to redish and respace, As a bike mechanic doing it "right" is the only way I like to do it, but the reality is if it works and you are happy with it then great, runn'er
The problem Ive oftenrun into doing conversions is that even on the inside of the spider the chainring cannot get properly aligned with the cog, with the added tension of a singlespeed drivetrain the chain is sent at such an angle that it is noisy and clunky, the angle of the chain is not an issue when you have a derailleur to relieve the chain tension and hold it in proper alignment before the freewheel wrap.
But like I said, if it works and you are happy with it , wonderful, especially if you want to have the gear option still there, but know that you can likely get it better if you need to.