In general, handyman construction practices are not recommended by home inspectors. As is typical in historic homes, certain liberties with respect to common building practices have been undertaken over time. While we can’t really bring historic homes per se “up to code,” significant handyman shimming practices are be logical to repair and improve. What really drives pricing is access (i.e., how much space is there underneath the home for contractors to work?). If it’s really tight, it will take more time; sometimes, excavation is required which drives the price up too. If you do require excavation under an historic home, make sure the contractor doesn’t get too close to the foundation or footings, as this would be a potential structural problem too.