Most DL and all DR came from the factory for 1R film.
All of the 70 series Filmos have the same basic transport design and modification of the sprocket capstans is really easy. I've done it on a 70A, 70DA and a D, all transport without any issues. You MUST pay attention to the gear mesh of the sprockets and the camera or you WILL eff up your transport. The pull-down claw also has to be clipped and to do this you have to get really intimate with the foil shutter. It is very pliable but once bent is a royal PITA to get straight again so it doesn't rub on the shutter chassis or jam completely. That said, don't warp, wrinkle, bend or whatever the shutter. Also, don't cut off the wrong pull-down claw. Check three times, or even better, use a paint pen before you take the shutter chassis out, mark the claw to be cut before any surgery is attempted. Also, you need to file smooth the remnants of the claw and make sure none of those filings get into the camera, in the shutter mechanism or the spring motor.
Modifying to Super-16 is possible but if you're using fast lenses or short focal lengths with constrained image circles, you'll get offset vignetting unless you actually machine a new turret to move the axis of the lens over the new center of the film. If you keep the apertures smaller and the focal lengths longer, you don't need to do this. I'm a real stickler for distortion and balanced images so I will always stick to 4:3 on my Filmos. I think a better solution would be to use anamorphics.
The turret VF is the stumbling block for many zoom lenses, especially those with reflex finders. The flange bases tend to be wide so you can't stick the lens on all the way. Add to that, the turret center nut usually prevents mounting of a lens fully. Even 1/6 turn will not allow your lens to reach infinity. The D and DA have a reverse-Galilean finder and is much shorter, no VF turret, so they are the only Filmos with a lens turret you can use a good C mount zoom or C mount adapted lens C-SLR like Nikon.)
If you modify a Filmo to be reflex, you can't have a turret at all and you're creating a single-purpose camera. It can be done but you need a good machinist and you need a budget for tools and dies. The steel of the shutter chassis which you'll have to drill into is hard as a coffin nail. Extremely good stuff. I think it's blued tool steel. You'll scratch it with a file, no problem but you'll also eat up a few drill bits. This is also why it is such a pain to widen the gate to make it Super-16. If you want to put a reflex housing on this, I'd suggest using a Leica Visoflex and pulling the pellicle mirror out of a Canon EOS RT. You would have to be extremely precise with your alignment and image circle placement. You may want to use a laser bore-sight. This is actually a pretty cool idea...
Come to think of it, if you're doing this, get a 70HR or KRM so you can load up 400ft cores instead of 100ft. If you're working at 24f/s, this gives you 11:06. You'll spend more but you also won't be changing reels every 3 minutes. You'll be able to have a few ready-loaded 400ft mags (if you're lucky and spend enough to find more than one.)
Otherwise, get a Bolex Rex, have it CLA'd and have a blast. One thing you can't do with a Bolex that you can with a Filmo is motorize it with a portable, battery operated drill.
I currently have a 70A, 70DL and 70DR. About to get into another, late DR. I just gave one away to a fellow RFF'ers kid for her use after film school.
I have a few recommendations for anyone looking to purchase a Filmo. Things to look for, expectations, etc.
As for maintenance, it's pretty easy. Clean it, lube it, shoot it. Wash, rinse, repeat. Never dry-fire the camera above 32f/s. The claw needs a bit of drag and stability from film to prevent it from hitting the edge of the gate/pressure plate. A few Filmos have slightly bent pull-down claws because antique dealers or idiot kids thought blasting it at 64f/s was cool since it sounds like an F-104 engine spinning up for takeoff. "Tested at all speeds" needs to be taken with a grain of salt because if the estate seller or someone's grandkid doesn't know this, he'll "test" it and unknowingly ruin the timing. The claw can be bent back but it's easier to buy a new one and repair it right.
Feel free to PM me for more questions (and my email address) or we can keep the discussion going here.