Ah, it's the weekend. Time to relax and figure out why my wireless access point periodically goes crazy and requires a reboot. Well that's the problem of playing with new toys, but it's really nice to wander around cleaning with a laptop near me at all times.
I'm not sure why you think using spaces instead of tabs will make source more difficult for someone else to read. At worst, it'll make them read it exactly the way you wrote it. How is that bad? If they don't like your style, they'll have problems anyway... there are more differences between C styles than tab stops.
If you only use TABS at the beginning of lines, you'll probably do alright with people using different tab widths. But sooner or later people will want to line up things which come after text... maybe variable names in declarations, maybe comments after code. That's when tabs are a big problem, because what lines up for you at 8 spaces per tab may suddenly not line up at 4 spaces per tab. Spaces don't have that problem.
Funny thing, I also have a MARC binary->ascii converter. I wrote mine as part of a larger project to make an EndNote-like app for X. My MARC converter also can display human-readable names for fields and subfields, btw.
My project has been put on the back burner, but if you're interested in something like that maybe we can get it off the ground.