Yes, you can make a leaf armor set with 100% LRC with those tools (though the leaf armor suit doesn't have a hat/helmet, so you'd have to make a leather cap or use a hat from loot to complete the ensemble).
I made a 100% LRC set of leather (the human equivalent of leaf armor) 3 nights ago using spined kits (took about 2 and a half full kits, so the 3 kits you have should be enough, since one of them is a horned kit and gives better properties).
Do you want luck & high physical resist (but low in other resists), or just resists, to go with the LRC?
If you want luck, use spined leather; otherwise, use horned & barbed leather (horned gives one less total resist than barbed, but the resist bonuses are much more balanced)
I'd start with seeing if your brother's tailor character has learned the recipe for "Stitcher's Mittens", and see if he has the resources on hand to make them (or even has a pair already made to use). They are a special type of leaf gloves that give a bonus to healing, as well as 30% LRC. You can then dye them to whatever color you want using a leather dye tub. Or, you can use that gold and buy the mittens cheaper than what you'd probably pay for the special ingredients to make them.
That will get 30% of the 100%, right off.
Now, find a hat, circlet, leather cap or a helm (the helm will need to be Mage armor - the others automatically allow regeneration) that will give you LRC, or other bonuses you want. Only the leather cap is craftable by a tailor, but smiths can craft magical circlets or metal helmet types with a runic hammer (circlets are better since you don't have to waste a property on mage armor). It would probably be easiest to craft a leather cap, or just buy a good piece of headgear.
Now, start crafting the other 4 parts (since if you follow this, you'd have gotten Stitchers for your gloves). I'd probably start by taking the spined runics, and making 10 of each part (including the leather cap if you choose to craft, rather than buy, headgear). If any of them are to your liking, set them aside.
At this point, see if your suit totals 100% LRC yet. There's a cheap minor artifact bracelet called the alchemist's bauble that gives +10 magery and 20% LRC, if you're within 20 points, if you have room to use it (you may have other jewelry you want to use).
If you can get to 100% LRC (or very close to it) with less than a full set of armor, put on all those pieces (going for the best properties and resists one can get from those pieces), and see what parts you have left. Make those missing parts with the horned runic, going for pieces that will improve the lowest resists, finish off LRC (if needed), and add other bonuses.
Once you get a complete suit with 100% LRC, look at your worst LRC piece, in terms of resists and/or properties. if you have any horned kit charges left, start making new pieces of that type, trying to get a piece that would make the suit better, if swapped in for the older piece.
When you're done, you should have a 100% LRC suit with resists in the 50s up to max (which for an elf, would be 70/70/70/70/75)
