Buying My First Muscle Car 1973 Duster 340 Interior Pic

I just got the VIN number from the owner. The title looks good and is under his name. However, I decoded it and it looks like the original car had a 318 in it.
G = 318 150HP(net) or 170HP(net) 1-2BBL 8 CYL

VL29G3B604679

I'm hoping the previous owner dropped a 340 into it but I'm starting to get my hopes up :/