Matthew:
It's worth reading this ''article'' about 'warped' discs.
As Roger says I would get new discs, but I would also get new pads, the old ones may be contaminated. I used M1144 front pads when racing in Classic Grads, I thought they worked really well. I used part number MGB535M1144 which has a greater pad area than MGB533M1144, which is a good thing.
It's worth getting the corner weighting checked.
Richard is right about camber possibly being a factor, but IIRC camber cannot be adjusted on a Classic.
HTH, Mark