I heard many times that my GSF400 was "too small" for freeway use.
Holeing a bunch of CBR600s and YZF600s and holding them down until over 75 mph shut them up.
Yeah, I was at 7000 rpm at 70 mph, but I had a 14,000 rpm redline.
Same goes for 250s. It just depends on which 250 you are talking about.
I've reached top indicated speed on a Honda CMX250 Rebel. About 80 mph It doesn't have a tach so you have to go by the red-lines and gear numbers. It takes a long stretch of level pavement and some creative (and not so safe) tucking techniques. It is not a bike I would recommend on the freeway. I haven't tried it on a Suzuki GZ250 but I do not imagine it's much different.
The Kawasaki EX250F Ninja is at about 7500 rpm at 60mph. That sounds terrible but it redlines at 14,000 rpm. Starts to pull hard (for a 250) at 8000 rpm so there's still some power left there. 9000 rpm at 70mph. Still pulling. Tuck in and you'll get to the century mark. Freeway is no problem. The Ninjette is one of my favorite bikes to ride 10/10ths on.
Hyosung GT250R is a little more difficult. It doesn't accelerate as well at freeway speed, but it is a bigger, more comfortable bike.
I haven't ridden the Honda CBR250 yet, but I have a feeling that it is between the Kawi and Kimchi burner in power.
The Chinese Lifan clone of the V-star 250 is no good. Sub-Rebel level of power. and then they put weird styling flourishes all over it like chrome studs on the seat. I was pushing it hard to get it to 65mph. It was still a relatively new bike so I didn't top speed test it but it's probably no better than 75. Chinese bikes are notoriously lean, but I don't see a jetting change netting another 30 mph. I'd honestly rather have a Cleveland Cycle Werks bike if I had to have a Lifan built engine. Then it's a CG250 OHV Honda clone and stupid easy to maintain.
If you gotta' do a 250 cruiser, see if you can find an EL250 Eliminator. All the Ninja mechanicals, Eliminator styling. Riding buddy of mine took a trip to Nebraska on one. Didn't get run over on the Kansas turnpike.