Your burl buyer sounds like he can have the rough blanks cut. Most gunstock wood is quartersawn for best figure. If he can cut the rough blanks, then you will need to seal the ends, to prevent cracking and let it dry down to about 8% moisture. About a year process unles you have it kiln dried.
Is your walnut English walnut grafted on to black walnut, claro, roots? The best figured wood will be crouch where two limbs run out. Crouch wood for the butt and straighter grain wood for the fore end to lessen warping after fitted to a rifle.
If this is orchard wood that was irrigated, it will have larger pores then old slow growth walnut. Less desirable, but can still can have very good figure and make the 200-400 dollar range of gunstock wood if you are lucky.
I have been lucky enough to handle $2,000.00 Circassion walnut gunstocks brought in from Turkey. The wood sold for that price for one stock and that was 20 years ago.
RELH