My plans for "conversion" of levels is to use a rough estimate based on the idea of the "average encounter."
I like the way you did this, NobleDrake, but keep in mind that your chart is designed to match XP totals (encounters) between 3E and DCC and not actual character power.
My rule of thumb is more like 1 DCC level = 2 3E levels, so that a 10th level character in DCC would roughly equate to a 20th level character in 3E. This is purely theoretical, of course, since there are so many random elements that make it hard to really compare the two games.
Anyway, that's how I do it.
It certainly is very hard to compare... even trying to use party strength relative to monster strength doesn't really seem to work - critical hits are much more pronounced in effect and very random in their actual potency, and there is no hard math to how much to-hit a warrior is going to build up.
In 3e you know when your party is ready for facing a Storm Giant and it being a hard challenge, but doable (around 10th level)... but in DCC going up against a Storm Giant at 10th level has you staring at an extremely dangerous fight that will only be won with luck (whether in the fight itself or in all the things that led up to that point, like having a warrior with a good strength and luck who happened to acquire a magic weapon of his lucky weapon type) mixed heavily with tactical decisions and a unified team leading the battle.
I went with average encounter "balancing" between the two because, when converting an older module, I find it easier to tweak the numbers on the monster stats than to tweak what the encounter is or how many encounters there will be. I actually run that way without making any conversion notes before hand to save myself from having any prep time other than getting out the dice and pencils.