Question for those that weld floor pans Options

[MrHyde]

I'm almost ready to start fitting the rear floor pan section and weld it in, but i have one question.. When I cut the old floor pan out, I cut it short by about an inch to inch and half.. I figured at the time I would trim it for a proper fit and sort it out when I was ready to weld.. Well that time is here.
Should I cut the old floor back so that the new floor pan butts up against it and butt weld the whole cut line (not as pleasant ) or perhaps pull down on the extra inch or so ( after drilling out the spot welds ) of old floor pan and have the old floor overlap the new floor pan and join it with two fillet welds.. I'm thinking that it might be stronger if I overlap the floor sections but I might be way off base here.. What would you guys do?? set it up to butt weld the floor sections together or set it up to overlap the floor sections.???

Thanks !
Mike