Keith,
It sounds like you have have little experience in fitting Parker stocks. Believe me, there is a lot of variation from gun to gun even within the same frame size. Differences in the hand filing of the frames and also the various drops have a large effect on stocks fitting different frames. The tangs on the frames were bent by the stock fitters when setting the drops for the stocks.
And like i stated, when it comes to stocks, 2 and 1-1/2 frames are interchangeable from a dimensional standpoint. The differences between the two frames sizes is in the height of the breech balls. Nothing to do with the widths or heights at the stock head I answered the OPs question accurately.
And we are talking about Parkers here, not Lefevers.
Parker stocks were put through a profiling lathe. The blank was roughed out on a band saw and then the profile of the stock from the wrist back was roughly turned. Yhe stock head was left In block form. The top and bottom inletting was roughly cut. The inletting was finished by hand and the cheek panels and wrist were shaped all by hand as well.
I personally own a Parker factory turned and unfitted stock, and have seen a number of others. So I can attest to this.
