Reach, followed by Stack will tell how a bike will fit.How does one build a custom bike without knowing how it's gonna fit?
Use a modern/progressive/slack size chart like Canyon has.
Im fairly confident your Reach is 450 mm
HTA combined with Chainstay will give you a good idea of how a bike will ride.
I looked into building a hardtail frame up and it was beau coup dolares that I could not justify.