I've been considering replacing my woodstove. It's small and I have a hard time fitting the occasional long chunk of wood inside. My brother-in-law is doing some remodeling and is getting rid of his woodstove. It's nice and in good condition, but has an 8" flue; my current chimney is only 6". I know that 6" is considerably smaller (28 sq in cross section versus 50 sq in for an 8" flue), is it safe to neck an 8" flue down to 6" to fit the existing chimney?