Tom,
I recently ordered a Galazan's Trojan buttplate to replace an incorrect flat Dog's Head that was on a gun. $30 later (they were on sale) I also had a buttplate made of probably correct material, but it was 1/8" too short at the top. I did not want to plug and redrill holes to make it work so back it went. It was not the best looking piece either, but to their credit they gave a full refund.
I have used these buttplates for project guns with good luck. Some people may frown on them because obviously the originals were not plastic, but they can be easily molded to the stock once heated without worry of snapping them like hard rubber, and they are oversized so they can be made to fit.
http://www.gungrip.com/items_457.html
If someone cringes at using these, sorry, but they help rescue junkers nicely.