made a few shallow sumps in the past, they are a twerp to do. makeing the sump shallower is easy but you have to shoretn the pickup, problem is do that and there is bugger all oil in it, so you have to put wings on it then getting at the bolts is fun
Did you not have major problems with distortion and sealing with these? The suggestion of running side compartments for extra capacity is the same as what Shrick run on their (expensive!) sump pans and is a good idea if you do go this route.
IIRC the earlier (pre-85) K-Jet cars had a shallower sump and oil pickup (they certainly run with a litre less oil in them) but I could well be wrong on the sump depth. Saying that, they did have solid lifters and not hydraulic......
As for everyone elses advice that you should raise your car being unhelpful, well if the answer is so bloody obvious that you cant see it then clearly you need it pointing out

. They do handle like crap when they are that low too, Ive found this on both of the Mk2's I have had......