If it was me, I wouldn't let the sapwood to heartwood ratio get too out of wack. If it appeared that it would go much beyond 3 to 1, I'd consider thinning the sapwood. What are your sapwood and heartwood thicknesses now?
I can't tell in the pictures, Roy. Is it faceted yet? or still square/rectangle?
Don't forget, when you round off the belly, you're gonna lose some weight.