Blimey, confusion reigns!
If you move the handle down 1" it makes the top limb 1" longer and the bottom one 1" shorter, thus the difference between the two limbs is now 2".
However I'd say (IMO) if you simply make the whole thing an even taper away from the geometric centre without any seriously raised handle section, it's much simpler and more like a ELB. If you do insist on a raised grip, it only need be 2" long as that's about the size of the depression in the centre of your palm, the remaining handle length will be the fade from that 2" section down to the limb. I personally feel a lot of grips are waaay too long, but that's just my style and I only feel qualified to comment on ELB.
You can find the best arrow pass/grip position later. If you want a fatter handle you can add a bit of leather on the back before you wrap it with leather (this also rounds off the flattish back).
Don't get suckered into marking out a Yew stave as if it's a perfecty even block of wood, go with the flow.
With a long bow, it's all less critical anyway.
Del