I generally have full width say 30mm for a centre section about 6-10" either side of center (yes I know I'm mixing metric and imperial
but mm are v good for width and thickness). So your 1 1/4" looks about right
From there I do a straight line taper to 20mm at the tip*, BUT, once it's drawing say 20" I do extra width taper over the last 6-10" or so to blend it in to a narrow tip for the nock which is as small as you dare make it
.
I've just measured my 90# Yew flight ELB and its 10.5mm where the horn nock meets the limb so your 3.8" is fine, mind I'd have left it wider for initial tillering.
Some people make 'em linear taper all along, I like the slightly "Spitfire's wing" look where it's a slightly curved taper. Starts of gentle and then tapers in more near the tip.
Hope this is some help
Del
* The extra tip width during early tiller helps avoid it bending sideways. Similarly you can leave it a little wider all over until braced and moving, then give it a lick over the belt sander to tidy the width down.
