Great work, I have the Sealion on my "to build" list; I consider it the most refined ETW's designs. I am now building his Wallaby borrowing many of the construction methods from the Sealion--such as main ball bearings in bearing holders and the arrangement of the timing case.
Have you decided how you are going to fabricate the main center bearing? Will you use ETW's design of 7/8" leaded bronze rod? I am still noodling on this one.
Good luck, I will be closely watching your progress.
Yes the centre was completed partially when the crankcase was machined ( the bearing cap ) and the bearing was made after the crank was finished and is now installed with the crank.