Yew Primitive Progress

I put a loose string on the bow and put it on the tiller, it harly flexed at all, so I've been removing wood from the belly. I'm in danger of removing all the heartwood at some points so what do I do?
There are several options:-

1. Make the bow narrower.
2. De-crown the back.
3. Painstakingly take 1/8"-3/16" off the back following a growth ring.

I'll end up doing a sort of combination of all 3, I don't want to go too narrow and end up with a longbow shape, and the growth rings of the sapwood are very fine and would be a nightmare to follow.
Bearing in mind that my Hazel bow which is de-crowned is one of my best bows, I shall mainly go for option 2, but I will try to keep the growth rings tidy and I shall doubtless make it a tad narrower as I adjust the shape and alignment of the string during tillering.
The bow is likely to move a bit during tillering as it has some 'propeller twist' in the stave.
I've been working on it in short bursts over the weekend, but I've also harvested some Laburnum, it was standing dead in the garden but was a bit awkward to cut down.
It decided to fall whilst my wife was hanging out the washing and it fell across the line causing some consternation, the line snapped rather than twanging her into orbit.
The sapwood of the Laburnum was pretty manky and there was some rot at the bottom of the heart wood. It split nicely giving me one nice longish recurved stave and an odd deflexed bit with some knots. I've hacked off all the rot and got it into the garage (away from my other staves as I don't want any rot spreading). The ends have been painted with PVA. Hopefully in a week or so the remaining sapwood will have dried a bit and I can trim it down a bit more, check for rot and store it somewhere more convenient.