Ty, you are correct in that the old designs present many challenges especially when it comes to incorporating some modern concepts.
Although my Barracuda isn't a Sheeks design I had to work out several problems during construction. For example, the sleek narrow nose had to be widened by 1/16" or I wouldn't have had enough room hollow the cowl to clear the cylinder fins and exhaust flange of my Rojett .40. The nose also had to be lengthened by 1/2" because of my engine choice. Otherwise, there wouldn't have been enough room between the engine and nose gear former to install a 4 1/2 oz tank. I'll have to custom build the tank as well.
The original Cuda had very thin wing tips (3/32" core sheeted top & bottom with 1/16" balsa) and did not have a leadout slider. It was a challenge to add that feature. I think mine worked out very neatly, at least I'm pleased with it.