Rep Power: 0

I have a 2002 LX es1 and I don't like the gauges that are in it, but I like the look of the ep3 cluster and was wondering if they are inter changeable or how hard it would be to swap?

 
Rep Power: 511

sizing of the two gauge clusters are different, so you'll have some gaps (unless you get crafty with some fiberglass or something to fill the gaps). You'd still need to depin the connectors and get some EP3 connectors and rearrange the pins properly to get it to work right.
I ran a google search for this forum (bc the native search function admittedly kinda sucks) and you can find a bunch of threads about ppl asking the same thing, and a bunch of the same response that it's more trouble than it's worth

An easier swap (still requires some pin rearranging) would be to swap in an 03-05 cluster. There are a bunch of guides on this forum. I bought a cluster way back when to do the swap and got lazy and never did it.

There are also people that swapped in a DC5 (RSX) gauge cluster, and one dude that did an S2K cluster swap, but same issue with the EP3 cluster regarding sizing.

Regardless of what cluster you swap in, the ODO mileage is stored in the cluster, so for legal purposes, you'd have to have either a) a shop update the mileage in the cluster or b) put some sort of legal annotation of the mileage difference between the cluster and actual.