Do what you want , it is yours. My 2 centavos >>> these cars are not Ferrari's in value or a collectors dream car , they do have a significant nostalgic value and are an expression of their owners . They are great platforms to do a sea of modifications and if ''VALUE'' is a consideration , recent car magazines have indicated that resto moded GT classics values are on the rise. So the ones that own a moded S30 have the best of two worlds , classic looks and modern guts. PS: keep and guard the documentation and it's period engine/tranny/ plus what ever you replace from it , so if in the future that beauty that you will create is up for grabs, the new owner has the option to reverse it, if that is his or her will