Contribution analysis - using firm level data

Hello, I am conducting a contribution analysis of a "cluster" using a firm database of companies in multiple industries that are roughly part of the same value chain, but that may also export outside of the region. I would like to estimate these firms' collective contribution to the regional economy using an approach similar to the multi-industry contribution analysis here https://implan.com/v4/index.php?option=com_multicategories&view=article&id=660:660&Itemid=14. I believe I will be able to track down estimates of sales for each firm. So, assuming I will be able to get reliable estimates of sales and then map those to IMPLAN sectors, how should I "shock" the system? Would I still need to apply the reciprocal transformation to my own sales amount? Do I still need to edit commodity production to where each industry only produces its primary commodity? I want to capture the approximate supply chain linkages between the firms in the database, but not double count. Thanks