don't you think that an aircraft which was in one configuration 30 years ago may be in a different on now
Absolutely. However, to an engineer, configuration means configuration control (as an ongoing process). Your post wasn't clear as to your intent ?
I suggest, though, that your concern still revolves around AFM certification processes and who pays - an OEM just isn't interested in being a benign and benevolent institution - it's purpose is to make lotsa dollars. You want/need something out of the ordinary, then be prepared to fork out lotsa dollars for the paperwork/mod/whatever.