After noticing the glaring omission with the centre of the frame spacers, I remedied the situation today.
As can be seen below, the spacer that accompanies the kit has the centre removed, which can also be observed in a research photo that I took at Maldon of J 549 (I think). So out with the vernier callipers, black marker pen, drill bits, and files.
Moving the frames out to the correct scale spacing means that all attached infrastructure also needs to be modified. The first 'cab off the rank' are the two steam chests (I think that's what they're called). The piston centres in the two white metal castings are the 'correct' spacing of ~25.4mm when fitted to the unmodified kit .
However, this distance increase to 28.9mm when attached to the braod gauge frame. Therefore, 1.75mm has to be 'found’ on each side of the frames. This is achieved by removing material from the rear of the steam chest castings. In fact, according to photos of the original (and unsurprisingly), this will be closer to the prototype.
Before taking the knife to the steam chest castings, I used a black marker pen and scribed on the frames where they should 'end up' (thought I should make the most of the alignment white metal lugs that will be removed as part of the modification). I then marked scribed a line around the perimeter of the steam chest castings...and that's as far as I got...
I intend to use some coarse grit paper to remove the bulk of the white metal and finish up with fine paper. Unfortunately, my supplies of coarse grit paper have all gone...
It would seem that a trip to the hardware centre is required.
31 minutes ago