The MFI cars go for more money and seem to be more highly favored by collectors any day of the week. I have only had MFIs and never had issues. If you live in a small metro area there are probably not a lot of mechanics still around that can work on the old cars. They either
retired or passed on. One of the leading authorities on this topic is Ed Mayo from Mayo Performance in Euless, Texas (Dallas),
mayos@imagin.net . He handles all the Early 911 questions for PCA in the Pano magazine. Good luck.