mik said:Jan, thanks for the answer!
It was my fault because I didn't formulated question very well.
I found some heatsinks at italian shop of electronics components with good price .Dimensions are: LXW (1000mmX190) Fins are 50mm long and base is 5mm so thats why I asked about base plate.
Just a gut feeling, seems these are pretty good in this repect. Fins are a bit high though. How much space between the fins?