Not sure I follow as the Rookie and Sportsman karts all are on the 900-1010mm chassis with nearly every Rookie/Sportsman/cadet kart being 950mm. Although there are a few 960 & 970mm Benik and Merlin karts out there. Is your Arrow a very short wheelbase kart? If you are running 3-hole Yamaha Rookie you are not at any disadvantage on the 900mm chassis. My drivers absolutely dominated Rookie classes on the 900mm Praga at the local and national levels for several years before the 60cc micro classes and sanctioning bodies killed the class off.
I’m not a huge fan of the Arrow but I wouldn’t change off of it for wheelbase only if you are just getting started. Had a similar discussion in this thread with another Arrow parent with a very new driver: