the leftmost mark is a Czech (perhaps Czechoslovak) lion proof that’s been partially oblitered, the 4 digit serial number & underneath is the ‘block letter’ in this case “B”. the 2 circular marks and the 2 star marks are Israeli markings, but I don’t know their meaning. on top of the receiver, those large digits peeking out from under the scope base say “7.62” & the stock would have had a similar mark, telling the new caliber. This was something the Israelis were big on, because they used the rifles in both calibers for a bit, AND most in service were citizen soldiers & reservists vs career infantry.
more photos will help us tell you a lot, shrink them down to about 1mb each to upload here.
post war, the arms factories in Czechoslovakia had been freed from German control had lots of surplus parts & needed customers for their K98ks. The proto-nation of Israel was a major customer, though sometimes through arcane routes, to conceal the source. Depending on what’s under the front scope base, or other marks that may be present on the right side of the receiver, will tell some more history. It could be rifle assembled post war from ‘German parts’, or could have been part of an actual contract for Israel, marks or lack of them will tell. The conversions were done because the barrels needed routine replacement, & Uncle Sam was generous with ammunition in supporting friendlies.