Yes...my first thought train was the Mahasagar Exp. between Bombay V.T. and Madras Central which I designed around 1984 I think. My 2nd thought train was Brahmaputra Exp. between Bombay V.T. and Gauhati via Jabalpur-Allahabad-Varanasi-Patna.
I had also designed an all-AC Bharat Exp. between CSTM and HWH which had a running time of around 26.5 hours. But I assumed a max. speed of 130 kmph. Ironically, the schedule that I chose is very similar to what the Duronto does now with 110 MPS. So, dreams do come true :-)