I performed the automatic trans shift mod on my first van.  I had converted
it to subaru 2.2 liter though.
Made a big difference and worked much better with the subaru high rpm
engine.  If you're going to do it, you might want to replace the o-ring
when you have the governor cap off.
Word of warning that I have heard more than once:  If you make the trans
work harder by raising the shift points, you should think about converting
to an air cooler instead of leaving the stock exchanger.

I've got some pics (below) on the site of both projects.

Brent
www.weidefamily.net/vanagon/