Thanks for the suggestions. I was able to find an MD2B on Craig's List. I pulled the Head and the Oil Pump and both look to be in good condition.
David is partially correct in that the 1, 2 or 3 in MD1B, MD2B, and MD3B does refer to the number of cylinders. However, they share many of the same parts. Since these engines have separate heads for each cylinder, the heads are interchangeable as are most internal parts.
If anyone is looking for parts, ring me up as I now have an engine I'll be parting out.