olyguy: Check the Shotgun News - they often have a bunch of advertisements for replacement sporter stocks. Also, Boyd's will carry a replacement stock for that rifle. If it has already been sporterized, you can have your choice of stocks depending on what the trigger guard and magazine base look like - if they are still in the original configuration you can use one type of stock but if the magazine base has been flattened you will need a stock to fit that (which also gives you one more round in the magazine).
I would also ask if you do any of your own stockwork? I sporterized a P-17 years ago, like almost 40. The stock I installed then was as you describe yours, 5 or 6 pounds. I didn't look for another stock, I just recontoured and reshaped the one that was on there, probably knocking off a pound or two, and she looked bootiful - so bootiful she got stolen, dang! But, if you can't locate what you are looking for in a replacement you always have the option of re-working the one you have. HTH. Mikey.