Seems best option for bad quality kits and plans with disconnects is to buy a retro laser cut kit from a reputable laser cutter. It may cost a touch more but spares the aggravations one used to go through with poor fit and poor wood. However, the saving grace of the kits of the 1960's and 1970's were the very low costs of purchase. A seasoned builder could then use any truly bad parts as templates for duplicates from good balsa. Rest of the wood was more or less usable.

I just noticed my 1960's Midwest 33" span profile CL P-40 Warhawk has a warped 3/8" fuselage. Warp is at least 3/8" of an inch. I could probably wet it and try unwarp it, but may re-warp over time. I'm better off making a whole new fuselage. Besides, the old was cut from several pieces so it could fit in the box. It would be more robust as a solid single piece.

C'est la vie.