Need help.

Well, that is the port going to the exhaust. If it is welded or brazed, You won't have to worry about heat at the plate then, that's all. The rectangular port leads to the
plenum floor, so unless that has been sealed in the plenum( I brazed the one in My iron Super Six shut), You'll still need the block-off plate to stop a very large
vacuum leak!!!:thumbsup: