I've known a couple of people who installed these electronic units. From their experience, it seems that these are pretty difficult to get working and they are not completely reliable (one of my buddies had to have his exchanged).
There is a mechanic here in Dallas who has successfully installed them (both guys ended up taking their cars to his after they ran out of ideas).
When I had trouble climate servo on one of my 6.9's, I went with a used replacement aluminum housed version for about $120 on ebay. It was a direct bolt in replacement to the plastic housing one and it solved my problems.
The one nice thing about the electronic UT version is that it's a lot smaller and can be mounted remotely which frees up access to the height control valve.
With regards to floor pans, you can go two routes, the first being buying a set from the dealer. They are not that expensive with the mbca club discount and are a true fit one piece unit that will slip in exactly how it should.
I found this out after buying a floor pan from k&k which was basically 1/2 the floor pan for the same price as the dealer would sell me a whole one. As a result, I had to fabricate the other half using sheet metal and a bead roller. It was not pretty but did hold up quite well and once you clean off the welds and seal it, it does not look too bad at all.
I would seriously look at buying these parts from the dealer (after joining MBCA) before going to the other sheet metal source. I had a lot of problems getting the right part on time. Very nice and polite people, but on more then one occasion, I have had to cancel an order because I got tired of hearing one excuse after another as to why my order was not shipped.
For aftermarket sheet metal, they are the only supplier in the country for vintage MB's. It seems to me that they are fully aware of this...... so you can wait