Did he marry in Madeira? Is the name of the bride you mention anglicized? Meaning could it be Luísa Silveira? If not, unfortunately, given the limited information you currently have, it will be difficult to discover anything on your João da Silva. Not only is the name, as you said, extremely common in Portugal, but also, Madeira has two islands and the main island has at least 10 counties, and each county has multiple parishes. Without name of parents or parish where he was born, it will be impossible to pursue his baptism record. Let me know whether the Louise you mention he married is Portuguese as well? If the name of the bride was Luisa Silveira, I may be able to check marriage records.