curve and grading rules on the D&RGW and other Colorado NG

I'm trying to make an HO/HOn3 layout within a fairly limited space.

So my question now is what are the sharpest turns and steepest grades the D&RGW would allow on their narrow gauge mainlines? I intend on having the "Mainline" NG being representative the D&RGW Silverton branch and then having an inner track that can act as the Rio Grande Southern/Silverton Northern Railroad. All I have really been able to find within this site and in my books was the D&RG minimum curve was 24 and that was on the Hecla branch that had to have specially modified locomotives just to run on because of the 5% grades.

Similarly I read that the Chattanooga loop on the Silverton RR had 5% grades and had something like 30 degrees turns but I suspect that it had to have been much sharper.

I intend on running up to K-36s on the mainline and C-19s on the inner track with sharper turns.

Also I recall that that C&T has portions that are up to 4% steep but I wanted to confirm this here with the more knowledgeable on the subject

anything would be helpful