I recently picked up a ZZR600, happy with it so far but with any older bike you need to budget for a little TLC.
Now it's taxed, tested, new tires, fluids, filters and shock it stands me at about £1400 and has just turned 20k for a 97 E5 model.
Spending on the parts made a big difference and will having a bike the feels 'right' will help your confidence.
I'm 5'10 and can easily get both feet flat down with bent knees so you may want to consider something a little bigger. For a £1500 bike I found little difference in insurance for a sports 600 upwards.
I got the ZZR as my main requirements were a fuel gauge, more power than a CB500 and some wind protection. Looked at the CBR and the Suzuki but the Honda's were more expensive or much higher mileage the GSX / YZF were a little too track focused and I'd rather have a little space to stretch out.
Have you considered an SV1000 or a VTR1000 Firestorm? These make similar power but will have more torque so should be similar to ride. There's the triumph 955i etc.
Plenty of options. I wouldn't limit yourself too much on the engine size, a sports 600 can get you into just as much trouble as any other bigger bike. Something around 100bhp and up to 220kg should be fine.