There was a save attached to
http://www.bay12forums.com/smf/index.php?topic=151968.0 this thread, and since i had been looking at it (hauling is by default higher priority than designation work, and burrow conflicts can perma-spam unfinishable haul jobs, so designation jobs never start) i just carried on with it for a while.
I actively encouraged the raging (zombifying) prafane soot contamination and got lucky - exactly one dwarf was left after a while and all zombie forces were outside, punching each other. So i just locked the place and let the solitary farmer clean up. Since the whole population had been wrestling zombie weasels for several months, she like many others was a legendary fighter, wrestler and striker and fully tragedy-hardened. Consequently, she happily packed away all the corpses, memorised those whose bodies were unreachable and eventually made it to legendary engraver. Thing is, there's just not much interesting to do with a hermit (no need to worry about food, she was set for 50+ years) and the sole remaining zombie of significance was her sweetheart, the miner, who kept wrestling a solitary zombie weasel for years. Would have been interesting to find out what skills and stats he must have had.
What let me abandon the fort without trying anything fancier was FPS decay - on a 1x1 embark, with one dwarf and two zombies, FPS crunched from 100 to under 20 in three years. I've no idea what did that, i tend to have ~ 30 FPS with 60-dwarf forts on 4x4 embarks with thick tree cover.
Just out of interest, i went and "reclaimed" the place. The group stood around stupidly and couldn't decide to do anything while a zombie fisherdwarf waltzed up and bashed them to death with a woollen dress. BTW: zombie fisherdwarf, unknown combat skills, bashing things with a dress, unarmoured - 1; caravan guard Hammerdwarf, presumably moderate skills (adequate to skilled?), standard metal armour and warhammer - 0. More impressively, the zombie also killed both draft animals via punches and bashes with a soft object.