YOu are crazy to run any engine you care about, especially one backed by a manual transmission without a rev limiter. That eliminates the whole issue.
As far as revving it until every last amount of power is gone, bad idea, that means you went past peak power and you are on the significant downslide of the power curve and the next gear is in the wrong rPM as well. Dyno the engine or go to the drags, better yet do both. Know where the engine makes power. YOu don't want to stay in it until it's not pulling anymore. Sometimes going past peak RPm is ok depending on what the curve looks like and how fast it falls off. No reason to beat an engine for nothing.
