I read a post, and cannot remember where I saw it, but it dealt with a manufacturer who installed Sako type extractors on M700's.
What I read said the actual business owner was out shooting one of his conversions when some overpressure situation happened. The SAKO extractor blew out and put out his eye.
The owner then recalled all the rifles he had worked on and restored the rifles to the original configuration.
I wish I could find the post again.
The M700 bolt face is a solid ring of steel. Leaving it intact is a safety feature.
Anyway, the M700 extractor will wear out. So will the extractor on a push feed M70. When both of these rifle types ruled the match rifle category, you always heard of folks who needed to replace an extractor. I helped replace a M70 push feed extractor on the firing line. These shooters are the sort of folks who fire about 5000 rounds a year through a rifle, and in a couple of barrels, some parts needed replacing.
Heck I had a cocking piece nose break on a pre 64. The gunsmith who replaced it had replaced had replaced post 64 cocking pieces, but he was incredulous that it could happen to a pre 64. Well, it did.
And he wore out the magazine spring and extractor on a pre 64!
Don’t worry about the extractor on a M700. It will last a long time, probably longer than the barrel on your rifle. The M700 is a sound design. The military has used it for years as a sniper rifle without modifying the bolt face.