Any old mil spc rifle which has non-matching numbers is already "compromised" when it comes to collectors value. Also any old rifle which is useless because of bad bore or bad chamber is ok to sporterize because it’s effectively junk the way it is before your efforts.
Here are some pics of what I did from a rusted out VZ 24 with a cracked stock.
Is there anyone out there that thinks I hurt it's value?
it cost about $165 at a gun show, and I considered that to be a "top value" for the rifle before I started work.
I dare say, it's worth a LOT more then $165 now