The GS500 is a good starter bike, even two up. I weigh 275lbs and am 5’11” tall, and the GS500 I ride still gets up and goes…I’m not in anybodys way…0-60 is around 6 seconds with me on it, that’s Mustang GT territory. The Kawasaki EX500 (Ninja 500) would be another choice in the same bracket, except the Ninja is a little faster. If you get an older GS500E, they are naked and look similar to the SV650 without having that much power…I beleive the SV650 does 0-60 in under 4 seconds. That’s pretty quick for a beginner bike.
Just remember, a used bike will hold it’s value pretty good so having to upgrade next year isn’t as big of a deal as you may think. You will probably be able to re-sell your learner bike for what you pay, or very close to it.
PS I wouldn’t recommend going two up until atleast your second riding season…get used to riding the bike and learn the skills required, then add to the difficulty…