Bicycle Mechanics - Blarg! Chainline opinion!

So, I apparently the guy who gave me my 15t rear cog bench ground off some rust to make it look shiny, well as a result he bench ground a little bit of the little gap filler on the side of the cog so it doesn't sit flush with the lock ring anymore.

SO! I bought a new cog. Problem is the bike store only had 16t or higher, well my chainring was 42, and 42 16 is a little bit too easy SO, I thought, "hey I have a 52 cog at home!" so I asked him for an 18t cog.

I get home and I put the Chain ring on and find that if I put it on the inside of the chain ring holder thingy, the gear is too big and the chain rubs against the frame.

I put it to the outside and It looks like the chain line isn't perfect anymore.

My question is, how much angle is too much for a fixed? here is a picture of my two cogs:

http://i573.photobucket.com/albums/ss171/GlachDuwat/chainline.jpg

Now, the picture isn't perfect, and it isn't quite edge on with the read cog, but it's pretty close, thankfully, it's not edge on slightly favors the chainline, but anyway, I added green lines to show where the two cogs are.

Is this too far?

What options do I have?

EDIT: Additionally, I have some other pictures with a chain laying over the cogs, and a second shot like this.

http://i573.photobucket.com/albums/ss171/GlachDuwat/chaain.jpg

Here is another image with a chain on it. just draped over the cogs to see how it looks

you'll know it's too much when there's excessive noise or your chain falls off.

you'll know it's too much when there's excessive noise or your chain falls off.

Heh, I suppose that is true, I also read on Sheldon Brown's site that there are spacing washers you can get for your sprocket, if I get a lot of noise, Maybe I'll pick some up from the LSB.

yeah, you can also do the spacer method.