Gen7 1.3board with marlin 2.x firmware trying to update (is there a way?)

[wasteoinc]

This is partly a question , partly a tribute and a thank you :)

I have a Gen7 1.3 board with 644p@20Mhz repetier firmware and I was trying to update to marlin 2.x . Marlin still supports our boards , but platformIO and sanguinoglu (which also has 644p) seem to give an uploading error.

I then tried arduino 1.0.5 where we have the relative board files for gen7 but this old IDE doesn't seem compatible with new marlin firmware.

So my question is , is there a path/way to upgrade to marlin 2.x , or am I banging my head to a wall?
Has anyone done it?

The board belongs to a self made PRUSA 2 that still works flawlessly :)