Theoretically the split system maintains some braking if one half should lose pressure, it won't be much. It's strictly a safety issue, has nothing to do with braking capability under normal condition.
"Any leak" in a single system will not cause total loss, it will take a completely severed hose to cause a total loss. A leak in a single system will only become "total" if you allow all fluid to escape, that's more then a "leak". I've driven for months with a leaky wheel cylinder, as long as there is fluid in the master the brakes continue to work. Split or single is your call, strictly safety related and questionable in my opinion. If you have a total failure in one half you will lose your total braking system, the master does not totally isolate the two sides. Only 2 separate masters would maintain one half 100% should one fail. It will provide some emergency braking, once.
I drive with new hoses, new system etc, I don't worry about hoses tearing 100%. Although I guess shxt can happen.
Keep in mind I'm not recommending either method, just pointing out the facts.
If you use a drum master you have to remove the internal residual pressure valve for disc brake usage, quite simple. On a 60's single master the RPV is a small disc on the very front of the spring, remove and discard, reassemble master. Images available on google search.