I also made a modification to the cylinder tins. The credit for this idea goes to the engine builder of Skywalker's Type-4 in his Splitwindow bus.
With a Type-1 style or 911 style shroud the air now comes from the top instead of from the back like on an original type-4. With this mod air is guided around the heads towards all 4 exhaust ports. The original tins only have this at the number 4 cylinder. The number 4 cylinder already gets the least amount of air with a 911 style cooling ( The air has to make a S shape from the back of the fan to flow between the shroud and number 4 cylinder / head . Flowing air takes the path of least resistance. So without this mod the cylinder that gets the least amount of air flow is also the only one with a more restricted path for the airflow, The path of least resistance
are the gaps between cylinder 3 and 1 and the shroud, alot of air is lost without cooling anything.
Some before and after photos
Cylinder 1
Cylinder 2
Cylinder 3
Cylinder 4
And After modification
With this mod all the air is forced through the cooling fins off the cylinders and heads.