As the property sold is a plot, you will be entitled to exemption u/s 54F only for the investment in new residential house, provided you don't own any other residential house.As you are already having another residential house, you will not be able to claim exemption u/s 54F. The only scope for you is to invest the amount of Long Term Capital Gains (LTCG) in capital gains bonds u/s 54EC and units u/s 54EE to the extent of Rs 50 Lakhs each.
As there is stay in the high court for the registration, you cannot transfer the title in the property to the buyer, as the high court may not allow the registration in its final verdict. Hence, your LTCG will be assessable, prima facie, only in the year in which the stay is lifted and the registration is allowed to be done, even if you have received full amount of consideration and handed over the possession. However, the nature of your court case and stay are important to ascertain the facts of your case for the determination of the date of transfer.