Since some have asked about this before, here in my solution. JB Weld. Fill the holes in the later cylinders and sand them flat. It is easy to keep the cylinders horizontal. You can keep the O-ring in the Pantah head. For Pantah 650cc and below heads you will need to either widen the chamber to 100mm or turn down the top of the cylinder to 95mm. Many of these 80 and 88mm cylinders are in very good condition, available, and cheap. MikeV

Hi Mike...
From your build photos it appears the locating dowels are positioned differently or non existent altogether on the later cylinders. Did Ducati decide that they were unnecessary?
Flattop

I guess I get too careless about some of this Flattop.

The oil passage dowel at the top is in the same place. The small one at the base is in a different location; the gasket to be used can be placed on the base of the cylinder as a template and a new hole drilled where needed. I should note that the oil passages are blocked off with set screws in the case since oil lines are going to the cam caps, and the big dowel is there for location and “insurance” purposes. I still put all the O rings in place.

Also, I failed to note that the modern cylinders are bigger below the fins, over 96mm, as well as at the top, which are 100mm. So, they are not “dropins”, and some machine work on either the case or the cylinders is needed. But the same is true of 88mm F1, Paso, and 750 Sport cylinders; they do not fit a 650cc case. If someone is building a Pantah to 750cc, and cannot find good vintage cylinders, then it might be worth the effort to use the new ones.

Carlo machined the heads I am using to 100mm chamber diameter, and when I spotted the very-bare case on ebay I could tell it had been bored out —- that is worth about $200 in a machine shop —- if you can find one to do it for you.

MikeV