CJ, those plates are for replacement motors. You might not want one.
So far, from what I have seen, your stamp looks original to me and it might be the original engine .....
If your '70 is a very early one with a VIN somewhere near 11304412012015?
? or 012025??? then it might be original to your car.
Do you mind telling us your VIN?
Mine is 11304412012287 with original engine 130-983-12-00748.
Good luck. Discovering things like this is one of the things that makes this so fun.
Mark
PS: After closely looking at the picture of your engine number, Shevel's number, and pictures of the two I've owned, I would say, IMHO, that the last 5 digits were stamped by hand and the ones before that are very aligned, so stamped by hand more carefully, or with a tool of some sort. What do you think?