IA-66 with TPE-331 engines and intakes above the propeller looks to be a fairly direct replacement for the Astazou as both turboprops are direct drive rather than having the PT6A's separate power turbine. Absent discord with the UK prohibiting obtaining them, I would prefer the Dowty-Rotol prop to the McCauley prop and either to an equivalent Hartzell prop (case of experience with McCauley and Hartzell and hearing good things about Dowty-Rotol from someone with equivalent experience with them).