A dedicated survey programe The Nainital-Cape Survey was initiated about two decades ago aiming to search for the low-amplitude pulsational variabilities in a well defined set of Ap and Am stars. Initially, the Survey was started with the search for new rapidly oscillating Ap stars and later the Am stars satisfying the selection criteria were also added into the master list to search for $\delta$-Sct type pulsations. The Survey was conducted simultaneously from ARIES and SAAO in high-speed photoelectric mode using 1-m class
telescopes located in both the Northern and Southern hemispheres. For the current study, time-series data from Kepler K2 were analysed in search for pulsational variability in the stars observed under the ``Nainital-Cape Survey`` project. In addition, high-resolution spectroscopic observations were made using Hanle Echelle Spectrograph (HESP) to determine the atmospheric parameters such as the effective temperature , surface gravity , metallicity , the microturbulence velocity, the projected rotational velocity and the chemical abundances. The derived atmospheric parameters are subsequently used to construct stellar models for performing non-adiabatic linear stability analysis. Prior to this study, we have performed the time-series photometric analysis of 340 sample stars under the Nainital-Cape Survey project. We search for pulsational variability among the observed stars by Kepler and it is found that time-series data are available in K2 archive revealed 3 stars with pulsational variability. Here, we present the light curves, frequency spectra and derived various astrophysical parameters of these stars, namely; HD68703, HD23734 and HD73345 and classify them as $\delta$-Sct pulsators. Based on the time-delay analysis of the K2 time-series data, HD68703 and HD73345 seem to be members of binary systems. The fundamental parameters and chemical abundances of these stars derived from high-resolution spectroscopy are also presented. From the analysis of Kepler K2 photometric data, the 3 stars are found to be multi-periodic pulsational variables. The low order radial modes are found to be unstable in the performed linear stability analysis for models of the 3 stars. Particularly, for the models of HD68703, the unstable modes have pulsation periods in the observed range. From the individual chemical abundance analysis, HD68703 and HD73345 were found to be Ap spectral type, while HD23734 turned to be normal A-type star. Our analyses show that the 3 stars, reported as null results from ground-based observations, are classified as pulsating variables using space-based photometric data from Kepler K2. Therefore, candidates regarded as null results based on the ground-based observations could be variable if space-based high precision data are used.