I am really rather surprised no one has done anything with the VW Tuareg V10 diesel. Twin turbo, 320hp, water cooled and all aluminium except the bearing blocks.
I haven't been able to find out much about it but I reckon if I was looking for a 200 to 250 hp diesel this is where I'd start. De-rated it might not even need a reduction gear.
Possibly the smaller size of the pots allows light construction of the heads. Personally I think there are an awful lot of moving parts in a V10 four stroke and I like the idea of the Junkers diesel but the VW is available.