Another smoothed firewall question

[TonyL]

to answer your question. yes. you should remove with a cutting wheel any "raised" areas that would cause your new fabbed peice of metal plate not to sit flat on the panel. weld around the perimiter and plug weld in places so you dont get rattles. (dont forget weld through primer) Far less filler would be required this way, and you'll be far happier with the results.