I can only speak for the D1, but this will get you thinking.
The problem is that the 3" lift will give you less droop since the top of the shock has been reaised. So you will need at least 3" longer shock over a stock setup to get as much droop out of the wheel.
Longer shocks AND/OR lowered upper shock mounts will get you back the droop. Try to get at least 2" longer shock or 2" lowered mounts, otherwise it is not worth it. There are tricks to extending the shocks on the EE website.
If you do a 3" lift on a D1, and add 3" droop to your shock by longer shocks/extensions or lowered mounts, then you MUST extend brake lines and get spring retainers for the rear as well.
IMHO just the 3" lift with out extending shocks is not as good of a setup as just the 1.5" since you have lost so much articulation. At least that is my experince with both on the D1. You can always add spacers and other things in increments if you wish.
Brian