Producing a 50p output with mixed frame rate footage.

Hi! Hoping someone here can help me with this!

I'm producing an Australian surf video and I want the action scenes to be displayed at 1080 50p to get the increased temporal detail and to throw back to the old days of 50i Pal camcorders. 

The issue is I also have cinematic sequences of the landscape etc that I am shooting at 25p,

theoretically I should be able to just slow that footage by 50% and use it on the 50p timeline. The software should be able to just duplicate every frame and that would result in a 25p look in a 50p video. 

The problem is I only have options for frame blending! 

If anyone has a better solution for this I would be very grateful! I'd prefer to stay within premiere but I'm open to using other software.