Three observables of ultra-high-energy cosmic rays can be measured with present-day observatories: the energy spectrum, the distribution of maximum shower depths and the arrival directions. We use all three observables for a combined fit, in which the parameters of possible UHECR sources are constrained. The astrophysical model used in this fit is based on 1-dimensional CRPropa3 simulations, taking into account all known interactions. Then, these 1-dimensional simulations are reweighted to account for the three-dimensional source setup consisting of homogeneous background sources and a variable contribution from nearby source candidates. The signal fraction, as well as the size of a rigidity-dependent local magnetic field blurring, are part of the fit parameters. The influence of the extragalactic magnetic field is investigated, considering the low-energy suppression due to diffusion, as well as a source-distance-dependent beam-widening of the arrival directions.