Gee you guys get so technical, To all you people wondering about the distilled water, It's just cleaner and has no minerals in it, and is cheaper then dirt. about .99 to $1.39 at your local K-mart or wall-mart. To Cary Chiang, I had a 87 Subaru with the 1.8 engine it had two timing belts. I did not know what engine most swaps used. The reason for changing the water pump on the Subaru engines when you changed the timing belts is that you have to take off most of the same componets to change the pump. The theory is that about the time you need to do the belts or soon after you would need a new pump. This saves you labor costs.
My Subaru went 206,000 miles before blowing. In the time I had it, I changed timing belts 3 times and one time it did not make it to the 60,000 mile mark and left me by the side of the road waiting for a tow. Not to mention plenty of front end work and, Exhaust system repairs, Axles, wheel alignments, tires wheel balancing, And one cylinder head gasket replacment at 164,000 miles. All about as expensive as the VW. My van still has the orginal axles, Only needed Wheel alignments when any front end work was done, only twice in 12 years. The Exhaust is original and only needs replacement now.  I do think that the 2.2Subaru engine is a good choice in the Vanagon Since you would have the combination of sturdy chassis and a more powerful engine. But don't expect it to save you any money. And remember those pesky timing belt's can leave you stranded with no warning.
John 1990 vanagon gl