Tape restoration workflow using varispeed

In the old days, a common way to restore a tape or vinyl was to play it back at a slower speed to record it, and then play the recorded file at its nominal speed.
For example, if you put a tape of 3,80 meter on a Studer with 38cm/sec speed, it will play 10 seconds. If you switch the speed to 19cm/sec the same tape will play 20 seconds with half speed. 
Today, if you record a file with 10 seconds in 192kHz Pyramix and play it back with 96kHz (real-time src off), the play back is half speed, but the file is still 10 seconds long and will stop after the half of the music. And the waveform does not fit to the music anymore.
If a file sampling rate doesn't match the timeline sampling rate, Pyramix either sampling rate converts it on the fly (if the option is enabled) which is not what you want here, or simply reads the samples at the wrong speed, which is what you want here... but all timings are computed then on the wrong sampling rate and the clip is then too short, eg. half size in our example.
In that case, the easiest workflow would be to consider the 192kHz files as being 96kHz files, basically meaning you would just have to retag its header to change the sampling rate.