Ed, ATV Jacks are great, but they are difficult to get an engine off of because they are wide. Your only recourse at that point is to put it on the stand. The problem I have had with them is that they are also too short to get the engine high enough to get on the stand (at least the one I own). But I have used mine a few times for sure.
Here is a simple pictorial.... dimension as needed or scrap wood allows:
The green is 1 piece and the teal blocks are the same, just cut shorter and screwed in from below. Front of engine is on left and rear of engine is on right so planks go along the sealing line of the case not perpendicular. I chiseled out some bits on the tops of the end blocks to fit the case. the benefits are two fold: consistent location of the board and slightly better support. when ever I have to jack up the car I use it, not just for engine drops.
-Michael
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Michael 
'82 Euro SC 'Track Rat' 22/29 Hollows, 22/22 Tarrets, Full ERPB F/R, Rennline Tri Brace, Glass bumpers, Pro 2000's, 5 pts, blah blah blah
'13 Cayenne GTS