Standard van jack should be fine. Mines rated to 1750kg and you'd only be lifting one corner of the van,...
Are you sure about this nathanael , did you purchase the jack yourself or did it come with the motor you got ?
My mate got a puncture today in a expert van loaded with 400 ltrs of water it was front wheel drivers side, flat 400 ltr tank so the weight was spread about .
Jacked up the van and the jack was stripped of the threads , just like lozsing mentioned .
My mate ended up having to call the AA .
He was told that the jack would only be suitable if the van was empty .
This could happen to anyone of us at any time .
CHECK YOUR JACKS YOU NEVER NO WHEN YOU NEED THEM .