You probably know this but getting the sprues as high as possible improves the fill and detail. Good luck. It's really great seeing someone else doing this. Alex and I had trouble with porosity (tiny holes on the cast that show themselves when you machine the bore). Please let us know if you solve that one. Because I plan to go with an iron sleeve, it doesn't matter to me but I would like to understand it. I won't get back to my cylinder till my airplane is done and that might take years!