Hi Jack,
Since the E was restored years ago, the seat cushions were replaced with the only thing available - made with a very dense foam that doesn't compress very much. If you give it to a furniture guy, he can remove the black rubber baffle on the bottom, cut out a lot of the dense foam, replace the cut out foam with light spongy stuff, and replace the baffle. Leaving an empty void would leave the seat sagging and not match the other side. Leave the pass. side alone, only take short people for rides. The seat baffle can be left out too - you'll be a bit lower.
If it's still too high, remove the seat tracks and bolt the seat directly to the floor at the most rearward position against the rear bulkhead. That involves 4 new holes in the floor - the bolts screw into the seats from below. Most tall people must have the seat all the way back and don't need to slide them anyway.
A smaller wheel diameter - 14" or 15" - will give under dash room too. There are some nice wood rim wheels out there.
One odd thing. There are small "L" shaped shims that the rear corners of the side chromes rest on. Make sure they are flipped back and out of the way. That will give a bit more rake to the seat back.
All the above stuff is easily reversable to original when selling it.
If you had a crappy driver, I could tell you how to lower the floor like a 2+2 (and get 2 more inches), and enlarge the cut-out behind the seat for travel and get more leg room. Then you can get a 6'6"er in comfortably.
Phil.