The 250 will have better low-end torque. The 230 will have a higher RPM capability, so the weight of the vehicle you're running and the final drive gear ratio will determine which engine will serve you best. I can probably get the same horsepower from a modified 230 as a basically stock 250, but it will be turning noticeably faster RPM. A short stroke V8 like a 302 or a 327 can outperform a 350, but it has to be modified, balanced, and wound up like a bumblebee on steroids to do it!
Jerry
I've driven my smoking, low oil pressure 250ci enough to know I have plenty of power and rarely go over 2400 RPMs. With the OD gear I cruise comfortably on the highway at 2100-2200 RPMs. Sounds like a 250ci will serve me best.