panels have to be seam welded together where that was the original method of closure. Seam welding however does not have to be completed in one continuous bead or even in one continuous session, sensible heat reduction techniques such as step-back welding would be impossible if this was the case. All the rear footwell panels in the 156 147 and GT have holes punched in them anyway just ahead of the rear seat base lift for the draining of spills and condensation and these are the most common starting points for corrosion in my experience ( your pictures are typical of lots of 156 147 and GtS ) so holes in a panel do not in themselves mean an MOT failure. holes due to corrosion do usually signify serious thinning of the metal in the immediate area, loss of structural strength or safety device anchor point strength and it is this which causes the MOT failure. In short you can have holes but the MOT tester must consider the panel strong enough to do it's intended job, most don't have the time or resources to test this accurately so if there are rusty holes that shouldn't be there its a fail. if there are nice round or rectangular holes with paint around them it probably isn't.
Your pictures show a good degree of enterprise and congrdulations on that but I have to say youl get far better results by shaping the piece first. you need a press, which is fairly cheap from Machine mart but can also be hired for a day from various places and cut some strips of hardwood which you glue and screw to thick quality plywood at the correct intervals for the corrugations in the panel you need to do two of thewse so when placed face to face the strips interlock leaving about a 5mm gap between each interlocking strip. these don't need to be very long at all as the presses available are quite narrow place the steel in between and crush one down on the other then move across and do it again until you have the correct number of corrugations. once that's acheived move along and do another row till you have a long enough piece to cover all the corrosion. tack that on all over and then weld it at in short runs at successive points as far away from the last one as possible,( a bit similar to the way you tighten the bolts of a cylinder head) in order to spread the heat A.M.A.possible.
Last edited by Yorkshirekeith; 29-06-16 at 18:46.