Interesting commments. Dan, I have built several gunstocks from Myrtle. I have found that Myrtlewood, while sensative to moisture, can be sealed enough to limit movement greatly. Another wood supplier and I agree, from experience, that sealed thoroughly inside and out the wood moves very little. His personal Myrtlewood guns have been to Africa and Alaska without movement. My clients have hunted all over North America with the same results. However, let me also say that not all wood is created equal. Our results may not be the same as other stockmakers.
The comments about softness of the wood is all important. Until you get the wood in hand it is all speculation. Check over the blank and then make the decision. Your customer will respect you for being straight forward.
IMO if the stock is held low in this blank, one can get a gunstock with a pistol grip. Many stockers have other opinions. Yes, I like the grain to flow downward through the wrist. However, a Mannlicher style with an open grip(4 3/4 " to 5" from trigger) will allow the straight grain of this blank to not be a problem IMO. There would be enough supporting wood to minimize any breakage with the grain in the grip area with this design. An American style closed grip would have to be reinforced in some manner to stop any possibilty of breakage.
I make this after viewing two original Mannlicher stocks in my shop. A Model 1909 and Model 1952. Both stocks broke from abuse during shipping not usage. Neither through the wrist. Both have straight grain flow buttstock to nose. One is 257 Roberts and the other a 7 X57.
