I believe the only difference in a GN trans is servo and valving, I don't think it's anything too major that wouldn't get changed with a rebuild anyway. That's the other thing about 200s, I believe they're more expensive to build up, but if it's going to be in there a while I think it's worth it for closer gear ratios. PATC (these are the guys that make the Raptor 700R4) DOES have a different 1st gearset so first to second isn't such a major drop, but it's pricey. Search for "power gear" on the page.
http://www.transmissioncenter.net/competition.htm
http://www.transmissioncenter.net/competition.htm