Basically you're saying you want to use your 90 VIN on a home built 110. Is it legal as asked...no. If for some reason your vehicle gets inspected by a law enforcement agency you run the risk of losing it. In most states, California included, the frame VIN is the true VIN of the vehicle. To be legal, you would need to have a title for the 110 frame and register it as the 110. Then you'd have to figure out any CARB related issues.