switching salvage title to clear title

Never once, in 3 different states have ever seen the DMV Measure or otherwise inspect a rebuild for anything other than stolen parts. Your states safety inspection is just for safety items etc. Neither one of those entities would know if the vehicle structure was repaired properly or not. It's not what they're looking for.
That's true for Iowa. They check the odometer and check for stolen parts. Other than that, it's all about figuring out your taxes. Since they moved to taxing you for kbb value subtract the parts you bought.