A quick video showing ball rasp burr use on manifold floor. Note speed and pattern. Just keep it moving around, don’t linger. It’s not fussy or complicated. Slower speed works and offers some protection from burrowing and possibly removing too much material. This is Casual easy work.
Those all look good. As long as the edges are sharp that’s what you want. I’d send it.
What you can do is port the manifold and finish with your papers rolls in 40 or 60 grit and go drive it for awhile. Make some passes on it. Then pull it off and burr finish it and do the same and see what you think.