Scratch builders do not buy milled balsa, they pick out their own timber and cut their own.
I'm just now finishing up the conrod, piston, head button and head clamp on a scratch build with a ST .15 for power
. I already made the new crank last year. I did cheat a little and reused the old case, but built a set of full compliment bearings for it. True scratch builders don't use the standard "industrial swill" to power our planes.
Plans are just ideas, or rather suggestions as to how the scratch built plane project can proceed. There is valuable structural information to be gleaned that no true scratch builder would "look down his nose" at.
You could say that a TRUE SCRATCH BUILDER never has or will he ever lay eyes on anyone else's plans for advice, engineering, or inspiration...because that would only taint the purity of his work...so let's just get real.