Unless we have more details it is impossible to give an exact answer. The RIAA and the IEC RIAA playback equalization curves are significantly different from the the NAB/IEC curves for tape. Usually in order to be used with tape heads a phono preamplifier must be modified. Can we assume that the 40 and 68 refer to gain in dB and the 68 dB is a MC low impedanced gain?
The Eros Bottlehead can be used for both, but has to be fitted with a commutator to switch the equalization components and the adequate value components must be added.