A few weeks ago I swapped some ('82 westy) 2wd springs into my '86 syncro. Blog post here http://shufti.wordpress.com/2013/01/06/vanagon-syncro-front-spring-swap-and-radius-arm-bushing-replacement/

After some time driving on roads, and a trip on logging roads (albeit solo, and van not heavily loaded), I can report that the springs are working just fine. The modest lift has been been a noticeable improvement on rough roads, and the "springing" characteristics is not any different than the stock springs when driving on pavement (ie no difference in front end diving upon braking).

I can detect a little difference in body lean in turns - well it really is hard to quantify, perhaps it is just the slight lift increase.

Anyway, the swap worked out well, nothing crazy happened, was not the end of the world :)

cheers

alistair