Do it yourself!! You should really weigh each of the headweights. You'll need this data, plus the approximate raw, uncut weight of the shafts and the spec weight of the grips you are using. You always should follow the tipping recommendations set out by the manufacturer. You can tip a little more or a little less if you think you are between flexes, but keep it consistent. You'll also need to have an idea what the finished clublength will be for each club. Take all this info and plug it into the simple swingweight spreadsheet available at the bottom right of this page:
myOstrich Golf
Plug these numbers in, then you can manipulate the "added headweight" to get consistent swingweight numbers at the level you want. The easiest way to add weight with steel shafts is to pour lead powder down the shaft and plug it with a cork. You'll need a ramrod to do this as well. You can also purchase the tip weights as you saw in your 3i. Make sure your ferrules are big enough around to encompass the top edge of your hosel...you can always sand these down to size. Any more questions please feel free to ask .. Have fun !!