Yes, it’s unfortunate that a center point is not defined and the two curves are not parametric. I replaced loft/sweep with RevSrf (yellow group).
I adapted code from the first link I posted. The ramp shown is the maximum slope allowed by ADA standards. The ‘Rise’ and ‘Run’ numbers also affect the precision of this model, as you can see by enabling preview of the PLine component before Loft. Decreasing the ‘Rise’ value will decrease the slope and make more turns.
Spiral inside loft_2023Feb8a.gh (99.4 KB)
I’m done for now, back in a few hours.
P.S. Too late! Maybe later.