Most P45/P35 motherboards overclock very well.
I use a P5K-E from Asus, P35 and have an E2180 @ 3ghz 8x375 1.385 volts in bios running 24/7
I know the gigabytes are excellent overclockers also, many people with 2180 also get spectacular results with the gigabyte boards.
Not to sure about the P43 chipset, but I highly doubt your future motherboard is going to limit the overclock of such a processor. Anyways just as an example I have to bump my Vcore up to 1.5 just to get to 3.2ghz stable, most people seem to hit walls when going ~3ghz+ with the E2180. You might also want to consider aftermarket cooling if you intend to keep it at 3ghz 24/7 depending on the voltages it's stable at and if you don't always have AC during the summer.
After a bit of research I found this:
http://www.dvhardware.net/article25361.html
thinking about it, the FSB on the E2180 is capped at roughly 400mhz so I have no doubt the EP43 DS3L will do as fine of a job on a E2180, and plus PCI-E 2.0 I believe does have some benefits these days. Quality P45 boards seem to be roughly $50 more expensive, so they may not be the best value.
Finally, It seems most of the recent intel chipsets like the P35 run awfully hot, putting on a little 40mm fan with tie wraps may also be a good idea to help keep it cool. Good luck with your overclock, and sorry my post isn't really in order, I write as I think sometimes.