What would Britain have sent if Porter had commanded a Constitution-type heavy frigate instead of Essex?
Short answerThe suggested response is at least a razee and possibly Dixon with a 74-gun ship of the line.
NotesReplacing Essex with a heavy frigate armed with 24-pounder guns changes the force Britain would need to send. A razee is the proposed minimum reinforcement, with Dixon and a 74-gun ship of the line another possibility. This is a counterfactual response, not an account of forces actually sent to fight Constitution at Valparaiso. Whether Porter would then seek glory by challenging the larger British ship remains open.