If I did not plan to buy a bender or have access to one I would buy a Girard frame and then figure out the suspension.
You could do that by reading up and experimenting. Until recently there was a very cool on-line calculator to model suspension geometry. It's gone. Here is the old link:
Namesco. A World Apart
Maybe it is out there. Crap! It was a great tool.
You could buy several sets of plans and maybe learn from those. Do not use the equal length A-arm ideas presented on Girard's site unless you want crappy steering.