Of course an aftermarket cam is always nice, but you would require a little more than just new lifters with one (springs, maybe double roller timing chain, etc).
For now I would suggest getting a replacement stock cam, 2001 era if you want to be straight with emissions. The timing setup in our engines is flat tappet/non-roller cam and lifters, in other words the lifters "ride" directly on the cam lobes themselves. Thus, the lifters are considered "paired" to each lobe, as they will wear in tandem. While replacing lifters separately MIGHT not hurt a low mileage engine, I still wouldn't risk it.
Stock cams are relatively cheap, and it wouldn't be hard to remove in a TJ, just take the radiator out, timing cover off, gears, chain, pull valve cover, loosen or remove rockers/rocker bridges until you can get the pushrods out, use a Styrofoam lid or something similar to keep them in order, check "straightness" of the 'rods by rolling them on a flat surface, then use a tool to pull the lifters, then FINALLY remove the cam...
I'll honestly suggest returning the lifters and doing a complete aftermarket timing set, but if you wish to just do stock cam and lifters I totally support that decision.
I'll try to get you specs on different year stock cams, see if there is anything there to yield a power increase on the cheap.
Good luck!