In 68 the VON will match the fender tags bottom right 9. The only way to truly tie it together for a 68 is with the broadcast sheet which will have the VON and the VIN on the same piece of paper. Otherwise you have to assume the VIN was not replaced however the cars vin and the fender tag options should be a telltale that the car is correct. engine, trans, color etc. This didn't change until 69 where the vn was stamped on the hidden locations, but still used a partial vin on the engine and trans with very few exceptions where the whole vin was used.
On 67 and earlier you can still get the build card from chrysler to tie it together.