I just received my Chevrolet Inline-Six Power Manual by Leo Santucci (an excellent source for inliners) and he states that the 230 and the 250 are identical except for the the stroke. The 230 has a 3.250" stroke while the 250 has a 3.530" stroke. So I plan to measure this today and find out just what the heck I have. Thanks to everyone who has responded.