Three ways I have of looking at your figures:
a) Attenuation figures of around 15-16dB seem to get speeds in the region of 60-75Mbps
b) You have a noise margin of 24dB, which is around 18dB more than needed. For lines using the full set of tones, 3dB of margin seems to be able to give an extra 10-11 Mbps. If that were accurate, you'd have room for an extra 60mbps on top of the 40.
c) My old line had an attenuation of around 13.5dB. When first installed, it showed an attainable speed of around 90Mbps; as take-up increased, the attainable gradually dropped through the 80's to 78, over the course of 2 years. When DLM intervened, that dropped a further 6Mbps.
Take your pick of comparisons... but it looks like you'd have a top speed of around 80Mbps, when fewer surrounding properties have subscribed, possibly heading down to around 60Mbps when suffering higher crosstalk levels.