The early classics had the traditional 2 pc floorplate/trigger guard assembly and the later ones had a one piece tg/fp.
I converted an early sporter (classic) stock to the one piece set up it was a bit of a pain but not too much work.
The shank on my 375 was about the same as the replacement stock and I didn't have to remove much wood
in the forearm, inletting the bm was the hardest part.
Converting a new stock to the two piece deal might be easier
Even easier than that is getting PTG Obendorf bottom metal for a M70.
Chuck Nelson knows more about that.