What do you mean the Opioid conversion charts all give differnt answers OP? I use them all the time and I've not really had that issue to a significant extent. Sometimes you have to make sure that you adjust the level of cross-tolerance to a uniform level from one conversion tool to the next. The conversion of Codeine to Hydrocodone should be pretty straightforward. If it helps, to get a very rough estimate for yourself, you can adjust your dosage of Codeine to Morphine by dividing the dose of Codeine by ten.
This is a valuable calculation in this instance, as PO Morphine and PO Hydrocodone are roughly equipotent. Keeping in mind that these are all estimations and that cross-tolerance and individual metabolisms are always going to be factors, you can divide your Codeine dose by ten, giving you your equivalent dose of 3mg Morphine, which is roughly equal to 3mg of Hydrocodone if both are taken by the oral route.
I'm going to close this, as you can't get any better answers from the Opioid conversion charts/calculators. They are very useful and generally pretty accurate. Do adequate research though and don't ever take what one web-site says as fact without investigating other sites.