Building transforming tall bike

Hey all. I don't know how much help I'll get here since this is a pretty uncommon question, but I own a tall bike and I've seen this video of a russian guy riding a tall bike that can transform into a chopper like bicycle. It's not sold and appears to be custom made.

From looking at the video and poking around the internet, it looks like he's using gas springs on the back triangle to and everything stays in the same relationship.

I'm looking into building one and wanted to see if anyone here had advice/thoughts/other observations on how to go about this?