My mate and I have SS 456s. Mine’s got a sus fork but his is rigid (and 650b). It’s a great frame and rides well with a rigid fork. It won’t be that slack with a 440mm A to C rigid and can be built v. light.
I assume you’re talking about the 26er Scandal but I’d also consider the 29er. I have a rigid 29er Inbred, which is heavier but has same geo and is v. good. 29in suits rigid SS especially well IMO.
You’ll have to factor in either a tensioner or swapouts. Last time I looked, On-one were out of horizontal swapouts.