Mummdogg - Had a similiar problem with my 48 and solved it in a similiar manner. One side - passenger side - needed new inner cowls and floor panels with some work needed in the corner so we purchased the toe/floor piece and welded it in. The drive side was similiar but didn't need any work above the joint where the two meet so we cut out the area about two inches up to save the orginal holes and metal as much as possible. Put in a new inner cowl on the drivers side also. Had a little problem with the vent lever on the driver's side. When we were done it worked out great. Everything matched up fine and the seams are much stronger. Even squared the cab back up when we took out the sag from the rusted out corners where the cowls and floor meet. We did the outer cowls first then the floor and inners next.
You might want to check around though I think some catalogs have a variety of different parts and different prices. May find something that fits your needs better.
Higgin - didn't support the welds with anything but may have to go back and do that. I like the idea.
