Estimation techniques for party positions rely largely on three different types of data sources: political text, i.e. manifestos, expert placements, or voter perceptions as reported in survey data. While the comparative literature on party systems mostly draws on both text-based and expert placements to analyse party configurations, there are at least two broad strands of literature that face the challenge to combine party positions with voter preference data: the literature on policy voting, and on representation. Here, researchers often rely on voters’ perceptions of parties’ policy positions, as reported in surveys. However, this kind of data is scarce, and often only available for the common left-right dimension, but not for more concrete policy scales. Also, it is known that voter data on policy issues suffers from biases caused by persuasion and projection effects, as well as from differential item functioning. While expert placements of parties are considered to be of very good quality, it is unclear how they fit into voter preference scales. This paper discusses and demonstrates the combination of party positions from different sources with voter preference scales. A simple rescaling technique for party positions from expert placements is shown to perform very well in a spatial model of policy voting. It can be regarded a good substitute if party positions based on perception data are unavailable. This offers many opportunities for comparative researchers interested in policy voting and representation, who are often limited in their research by data availability.