Stihl 051 rebuild questions

[Coach]

I'm rebuilding this soon to be 051 (from TS510 parts) with the idea to use as a dedicated chainsaw mill with auxiliary oiler. So a question:

I have a new aftermarket cylinder kit that has a squish of .050" with no base gasket. Is this acceptable for this saw?

Another problem I have is the .404 drum sprocket i got is too small in diameter to fit the shaft sleeve. Am hoping to get a smaller sleeve or a sprocket that fits.