One thing is for sure, on SCs the font of the rifle's serial number suffix and the font of the serial number suffix on the mount bases are consisently different. The rifle will use a block style and the base will be more cursive.
On the HT in question per Dave, I have a few pictures. The rifle serial does not have a round top on the 3, the scope ring has a rounded 3. The barrel code also has a round top 3. Since this is built on an AR reciever, I looked at the font on a AR 43 I have. Note the gas shield has a round top 3 so round top 3s were used in some stampings. No other part I can find has a round top 3. There sure is a round top 3 on the ZF41 mount I have also.
When anybody says "absolutely" on a given issue with WW2 rifles or firearms, I get instantly skeptical. There is variation in numberous firearms made in WW2 and I see earlier thinking on whatever issue being shot down on a regular basis. For instance, traditional thinking was that only second B block and second K blocks were phosphate and had grooved wooden grips. I have since seen 2 matching original second A blocks in phosphate.