OK. I'll look for sheet metal & plate stock within the ranges you & Darwoodious have listed. I know Home Depot has flat stock & angle iron in 1/8", and 16g sheet metal. Square stock is limited to 1.25" x 16g. If the stock metal surrounding is substantially thinner, I don't see welding heavier stock to it as an advantage? Unless that's attached/joined where there are multiple layers, like the suspension attachments?
Should I plan on adding a reinforcing member within the rear upper crossmember on the '87? I saw posts regarding this, but I thought that was a early body issue. I don't recall MWB mentioning that in the kit notes, I'll recheck.