Honda still sells the Nighthawk 750 - pretty much the same thing they sold in 1969, with a number of updates. No car engine.
Of course, it’s significantly detuned compared to the parent bike, my 86 Nighthawk 700S. Redline 10,750, shaft drive, ungodly accel above 7K. Still keeps up with most 600-class sport bikes 0-60.
In the sixties, 250cc ws regarded as midsized. Now it is small, but with the changes in engine tchnology it apears that it will do just fine for me. What I do not want is a bike with a car engine in it. Meaning, I want a bike that I can work on, not something I have to take into the dealer every time it hiccups. Carbeurated, air cooled if possible, just a simple bike that is reliable.
After I spend a year or so on that bike I’ll know whether I need a 750. Would probably be a Honda Aero, a cool machine.
I have owned a SSE492 (car with 492cc) and have ridden around in other cars of about 850cc. So my predilection for something a bit smaller than many would like.
Can’t tell you howm any times I have stripped down, cleaned and repaired a carbeurator my sports cars. For about 40 bucks.