Was this ever sorted out? Seems to me that the real 48 could have just been missing the cowl tag like so many race cars of the day.
Usually this resulted in the whole firewall being cut out and tossed as well, so the lower hidden vin would also be missing. I knew a guy with a 69 z28 that he turned into a race car back in the day and he regretted cutting and tossing the firewall later on...
If the person who had this car with the vin plate was just honest about the missing pieces, it would have been a lot easier to understand. Especially since simple math figures out the correct body number without much work, you would think somebody would at least make that right. so far it looks as if its not right.