too 'big' for the Ninja 250

I take my new rider course soon, but as a newbie I'm taking the advice to start out low and slow so to speak...

I keep kicking between a Harley 883 Sportster (probably a used 2000 or up) and the Ninja 250, which can be bought new alot less expensive than the Harley sporster...

but I'm 6' and 250lbs..is that 'too big' for a Ninja 250, with a goal of going to an older 600 or 750 once I gain experience a few years down the road?  

No, you're not too big for the Ninja, in fact you have only 30lbs on me and my most fun rides have been on Ninja 250s and The Cagiva "Mito", a 125cc 2 stroke.  Having said this: Where are you going to ride?  Will you be on the Highway or on tighter back roads?  Look at the Ducati Monster 750 and 620, The Suzuki Sv650, and GSE500, these bikes might fit you better.  

I disagree with the small bike size as a new rider.  My first sport bike was a Yamaha RD400 (30 years ago), and I almost wrecked that thing more than once (2 cycle engines were something else).  I went through the marriage, kids, college, and back to the motorcycle 25 years later (5 years on my latest bike).  I got good advice from experienced riders and bought a Triumph Sprint RS (120 HP at the crank, 75 lb/ft of torque).  You know what, it's 10 times easier to ride than the older bikes, even 10 years back.  The power of the newer bikes are smooth, and the brakes and suspensions light years ahead of the old bikes.  You might consider the bike you really want, and just take it easy until you get the time on the seat, and you'll be glad you did.  However, there is a prerequisite, you need to take a riding course before you choose your bike.  You'll learn more about how to ride correctly, and lessen the affects of having a brute between your legs.  

I appreciate the responses.  I'm lucky that I life north of Fort Worth, so I'm not on the freeway unless i HAVE to get on the freeway. 98% of my driving is on twisty back roads, city driving light to light, and long stretches of 50mph and under roads.  I can even take Main through town and end up in downtown Fort Worth without leaving city type driving....

I need to hit the Fort Worth dealerships and go sit some bikes like the Sprint, the Ninja and the others. I'd like to end up with two bikes, a Dyna wide glide of 85 and up vintage, and a sportbike in the 600-900 or so range. Always liked the looks of the Triumph and Buells, so I keep looking towards those, and keeping the Ninja (or some other 'starter' ride) as a backup

KB