Honda 750 Nighthawk - intro'd in 1991 thru whenever they quit (IF they quit). 750cc DOHC basic. 750 yeah, but very user-friendly power characteristics should be fine for him. They'll easily go 50k miles.
Yup, 91-2003 with very few minor changes through the run, like the drain plugs at the bottom of the fork sliders disappeared in like 96 or something.
I'm the 3rd owner of my 92 750 NH, $1300 off of craigslist 3 years back. It's an appliance, hydraulic lifters and cam chain tensioner... so no adjustments to make. Chain drive. Carbs are pretty simple up 2 sizes on both jets and set airscrews to stock for a Vance & Hines 4:1
Mine has a little over 45K and it came to me with 31K miles. Lets see, Rotella 15-40, purolator filters, stock air filters, Sintered brake pads, same brake rotor as early CBR600/1000 and ST1100 so plenty of them around to tear up with rough brake pads, no worry about enough stopping power with the single disk either.
Be sure to replace ALL of the bushings in the front forks when you have them apart to change seals, not very cheap but very worthwhile and use OEM Honda seals too they're the best, 10wt fork oil is good. Michelin Pilot Activ tires are the hot setup, you can go with a 150 on the rear with no issues.
Plus you can probably find one of these bikes with low mileage in great shape, it was considered a wimpy bike in its day because sportbikes were what everyone wanted then, so lots of them are well preserved. $1500 should get you one under 10K miles.
PM me if you need a manual, I have a spare I can part with cheaper than you'll find a new one.
Alan