67 fb factory wire harness question

I'd go with a newer harness, in terms of work; i think painless will take a little bit more fitting but it will also be a lot easier to add on new things like door locks, power windows, alarm, etc...

I think the hardest part for me when putting a new harness was getting the wires to go through the firewall. On the 66's they have 2 master disconnects and i couldn't find any replacements for it, so i just used the old ones and spliced the wires.

Umm, i'd say quite a bit of time. Assuming that the factory one already has connectors and what not, i think installing a factory one shouldn't take more than 4 hrs. as opposed to something like a general one that can take up to 20 hrs for a first time installation.
It depends on which painless harness you get, according to the data they provided for the 67 mustang one it looks as if they have their terminals already connected. If so it wouldn't take any longer than it would to install a factor one. except the fuse box looks a little smaller so you might have to tinker around with that portion.
I've only installed an EZ wiring harness so i dont know much about painless or a stock replacement. EZ wiring is a general GM harness so it took a little bit of modification and was not preterminated so it took about 20 hrs to install my first time. now i can probably do it in 8 hrs maybe.

I was looking at this one i was looking at http://www.painlessperformance.com/webcatalog/largeview.php?SearchField=20121