hi when i did my suspension put gaz adjustable shocks on front and rear what work really well depends how far you want to go and how much you want to spend.
spec i did was
rs2000 multi leaf springs on rear with 1" drop
power flex and super pro bushes all the way round
gaz adjustable shocks front and rear
coil over front legs fully adjustable with 180lbs springs
rubber mounted bearing top mounts
twin cam front anti roll bar with double width mounts
car now handles like a dream ride is not to harsh but corners like its on rails did this on a mk2 4door but should be the same result on your van