Trashed driver's seat mount; now what?

["Chris Newbold" <cnewbold@earthlink.net>]

So I was trying to remove the driver's seat from my 1993 90
to bolt in a 5-point harness. The front of the seat is held
to the floor with two 6mm hex socket bolts which go down
through the floor and engage nuts which are welded to the
other side.

The first of these bolts broke free fairly easily; the second,
however, turned into a real mess. First, the hex socket almost
stripped out (as these things seem wont to do). I finally got
a sold fit and applied torque, and more torque and even more
torque, but nothing budged. Then the welded nut broke loose.

So, I had this bolt which just spun in the hole, and no way
of reaching the nut. Realizing that I'd already reached the
point of no return, I cut the bolt head off. The nut and what
remained of the bolt fell into the cavity beneath the floor.

How do I fix this? I have no idea how to secure that one side
of the seat, short of cutting a hole in the floor pan from
below so that I can put another nut on. I don't like that idea
at all...

This seems like another triumph of Team Doorhandle(TM). (It
seems as if quite a lot of LockTite had been applied to these
bolts, so that may explain why the weld failed...)

Help!

-Chris
1993 90CS 5sp 79k miles