Cannondale Hybrid conversion
I am close to your size...250 lb and 6’5”.
Last August I had a local bike shop convert my “jumbo” sized Cannondale Adventure 400 hybrid. The frame is built for us big guys and it has a front shock fork and seat post. I used a 750 watt Bafang mid-drive, new brakes, new Schwalbe Ebike tires, shift sensor, Brooks B17 Imperial seat, clipless pedals, and a decent sized battery (48/17) for range.
Original cost of this bike in 2003 was around $550, cost of conversion was around $700. I am very pleased with how well it rides and the performance of the motor. Wen I use my assist, it’s usually in “2” and in the middle gears of my rear sprocket.
So if you can find a regular bike that supports and fits you well, a mid-drive conversion and some other adjustments can give you a very good result.
Good luck!