@marlinjack posted:...Doug! You're 'Half-way Home'!! How about getting a 'Short' Pump Bearing Assembly from CVF Racing Water pumps, Rebuild Kit? If the Bearing Diameter is Larger, Bore the Casting to fit. If Diameter is Smaller, turn a 'Sleeve' on the Lathe, use Locktite RED.
I want to see You Succeed!! Call them up, I'll bet they can help You! Perhaps they would be willing to Custom Build a Bearing Assembly for You, Or, Already Have One in Stock! 'Ask and Yea Shall Receive'.
When it comes to taking Measurements for Cutting the Casting Neck. I Quote..."You Better be Right Mister! You Better Be Right!!
The Shorty Pump arrives in a few hours! You will hear from Me soon.
I would love to see you disassemble that new short pump to see what they did with the bearing but would never ask you too? 
A short bearing assembly is all that is needed, and some plywood for the cover! 
Cutting the neck of the casting is not even a high school shop project. Maybe a sixth grade thing? But the bearing, don't mess with the bearing! Not only is it a can of worms, it's probably radioactive too!