
Fun motoring for 5 years but now my mechanic and I are wondering about the structural capability of the conversion. The car has always been slightly bowed (gap at top of door is larger than at bottom and, looking along the sill, at the back of the door is larger than at the front) and has also flexed a lot during travel. There is a query as to whether the "bow" is currently more pronounced. Certainly now there seems to be permanent movement which is affecting the shape of the car, specifically:
The NS passenger door recently had to be reset to make it latch securely
The Front OS wing is showing signs of distortion which I am fairly sure is not impact related.

The conversion appears to have included:
seam welding an angle iron along the top of the existing sills
welding triangular corners between the sill and the posts fore and aft
welding additional plates along the underside at each side, between the sills and the rear suspension mountings
welding additional plates around the rim of the front wheel arches
probably more

Most of the welds appear to be structurally sound and there is no obvious signs of rupture or tearing. however, we are concerned that the conversion may have left a weak point, likely at the front of the sill, towards the front wheel arches, which needs strengthening.

Can anyone advise:
What is the best way of identifying the weak spot and the location for any strengthening?
Is there a plan which identifies the locations which should be strengthened when completing a conversion? Something that we can compare the existing work against?
Is there any other way in which anybody could help/advise in resolving this issue?
If not anybody likely to view this thread, who could I go to for (free if possible) advice?
