Abstract: MeV X-rays and 10^13 ph/s flux values were obtained for inverse Compton scattering sources based on injector designs from CERN (HPCI) and CompactLight. Coupled with a high-power compact laser, such sources could be used for FLASH therapy, nuclear waste management, or semiconductor wafer inspection. To determine the impact of laser misalignment in direction and angle, tolerance studies were performed for both sources. Furthermore, a numerical optimisation was used to design a small final focus system for the electron beam, from which realistic expectations of the electron spot size were obtained. Fabry-Pérot cavities operated in burst mode can increase the available laser pulse energy by several orders of magnitude. An optimisation for the cavity geometry and burst mode parameters was performed and revealed that a flux of up to 10^14 ph/s could be obtained, an intensity larger than any other existing or commissioned ICS source.