I am unaware of ready-made, off-the-shelf templates.
Both editions of Buchele's Recreating the American Longrifle have full size drawings included with them. Prior Mountain Bill may have a full-size drawing, as well. "Seeing through the Eyes of Yesterday ... The Kentucky Rifle and the Golden Mean," by Patrick Hallam (available from Dixon's) can show you the PC method of designing a stock. His very nice line drawings can be enlarged, also. Most suppliers have full size drawings for sale.
When drawing from scratch, scaling-up from a picture, or enlarging a picture on a copier, or projecting to a known dimension, I like to use 1" graph paper, available for flip-charts. It makes life alot easier!!! A full-size drawing can be copied in segments onto 8.5x11 paper and re-assempled on the graph paper. It helps to make reference marks on the original drawing to aid in re-assembling the individual sheets.
I like to use clear plastic for the template so I can see the grain clearly. Celluloid or acrylic plastic window stock works well. If I use cardboard or Masonite, I make it in "reverse" (cutout) so I can see the grain through the "hole." (trace around the inside.)
Good advice about the missing third dimension of depth/thickness. Not only in the wrist, but in the cheekpiece, fore-end thickness, and cast-off, too. I have fallen into this pothole myself!!!
It's more fun/practical to "adjust" stock dimensions to suit your build, anyway. Once you find dimensions that fit you, its easy to incorporate them into subsequent stocks.
Hope this helps.