The rifle in Senich's book you posters pics of is a Van Orden M70. A few of them were shipped to the Corps (my friend actually has a documented USMC one), but that's not the sniper rifle you're trying to build. From your posts, it appears that you want to build a modified sporter or a marksman stock version. If you want a Van Orden, just wait until one comes up for sale, he ordered around 3,000 from Winchester and sold a lot to the military, so original ones do pop up from time to time.
Since I posted the marksman pics in your other thread, I'll post pics of my 2 original USMC sporter M70's from 1942 in this thread. These 2 rifles were from the original shipment of 343 (that might be the exact number, but not too sure, too much detailed info to remember, lol) M70 sporters that were sent to the Corps.
Some of these guns were left in sporter configuration, some were turned into sporter stocked snipers and others were turned into marksman stocked snipers. These sporters are literally the base for both USMC sniper variants. All they did was modify or swap the stock (depending on version) and change the barrel.
The donor rifle you purchased technically isn't correct for a build since the 1942 M70's had the cloverleaf/doll head/whatever it's called tang. However, there were later M70 purchases by the Corps and those might have the regular tang. All of my original rifles and stocks have the early cloverleaf tang, so I'd assume those were pretty prevalent or the norm. Your bolt and safety are also the later type, but those are minor details. I have absolutely no idea why you're being told to remove the checkering, this isn't an M40 stock. The original sporter stocks have checkering (pics below). If you need questions answered, just ask me, I have original items, knowledge and experience. Don't mess with your current stock, sell it as is and buy the correct variant for your build.
All that being said, swap your stock and barrel, simple build. Finding a sporter stock with a straight comb won't be too challenging, get one off of Ebay or from here:
https://pre64win.com/collections/stocks?page=1
Finding a marksman stock is going to be more challenging and more expensive. You're best bet is to contact the guy in the link above. Barrels are another story, I'll just wait until you start another thread GI2
More info on the USMC M70's is going to be released within the next few years, I'm not privy to say anything beyond what I've observed and what I have in my collection. Here's my 2 original USMC M70's, they're the only M70's I've ever seen that are serial number hits on the list in Chandler's book, Death From Afar volume 1. They both came from a Recon unit in Montana:
One of them has a bunch of brass pins pressed into the stock, my best guess is to prevent warping in a very humid environment, like the jungles of Vietnam. This pic shows those pins:
