Ive built/repaired more banshees than i can remember,and I watched someone port my 88lt250r cylinder from start to finish,And what i saw was nothing your ever going to learn from a template. He said endless trial and error was how he learned.
Learning how to port from a template,is about like learning to paint a portrait with a stencil.
He was the same guy i took some ported banshee cylinders to,to check them out. The porting looked fine to me,but after he measured and pointed stuff out,he came to the conclusion that it wasnt even safe to run.