If you re used flying big ones, why the single requirement. Somebody else suggested a Seneca and i d agree.
Especially if you intend to do flying in the winter too, over mountains (Alps, Pyrenees etc), long stretches of water, why not consider the twin option.
Seneca's are a proven solid known ice platform for serious cruising and for 300K you get a hell of a lot more than if you choose a single these days...
In fact you ll pick up a very clean version III or IV for some 200K or less. That s a lot of money you can put in the tanks.....
If you do go for the Seneca, I'd recommend you get the Gami injectors and the JPI 760, with probes on all cylinders. It'll allow you to fly safely lean of peak (saves money) and allows you much better engine control.
I had my props also dynamically balanced and it's worth it, beautifully smooth!