Nice, the great thing about these projects is when you develop something yourself and it works like you want it too
The thing about quieting the chain - other than keeping it lubed, the only way to make it quieter would be to get a set of quality sprockets and chain and even then it's only a marginal decrease in noise. I suspect the "rag joint" style of mounting the rear sprocket (guaranteed to be off center) and the idler wheel contributes to the racket, but if it's bent inline with the chain than there's not much more to do.
Manic has quality sprockets and I'm sure you've heard of his adapter: SPROCKET ADAPTER
even separate from the noise issue, it cuts down on vibration and generally this is a fine upgrade to have.
I didn't build my bike for looks, I built it to go
The way I figure it, form follows after function and if it's well built and truly functional it'll looks fine to me