Gaps possible if you've got mismatched bodywork like my 03 tank and 00 tail. The gaps on mine aren't really noticeable unless you're up close and looking for it though. Hey, if you do the swap, make sure to post up pics and a how-to!
Jackal, if you want an 03 tail section, subframe, stock light, and other bits to do the conversion, I could sell you my stock bits for cheap. The tail plastic has a broken tab, but I fixed that by using an aluminum plate and bolts. I think I've even got the stock front seat. No tail cowl or rear seat though. I'd sell it all for $100 just to have it out the door and clear up some garage space.
All you'd need then is a tail cowl or rear seat, undertail (I can give you my chopped battery box for free until you find one on ebay or go with an ermax), bolts (tastybolts.com), and a tail tidy kit. I'd recommend finding an undertail on ebay though.