Your this cucurbit is appearing interesting to me. I had called it C. moschata largely on the basis of large leafy calyx lobes, but having seen your photographs more critically, I fear it may be none of the two. The hairy young ovary and leaves, I think may not identify this to be another Benincasa hispida. Perhaps both (including C. maxima) are known as Petha, one we commonly cook the Halwan kadu has yellow flesh and mostly orange yellow in colour (that could be your plant if yellow halwa kadu), whereas Agra Petha is white inside and ashy or whitish outside and is Benincasa hispida. May be you can check on ripe fruits to confirm.
Dr. Gurcharan Singh
Retired Associate Professor
SGTB Khalsa College, University of Delhi, Delhi-110007
Res: 932 Anand Kunj, Vikas Puri, New Delhi-110018.
Phone: 011-25518297 Mob: 9810359089