Lets suppose you had the engine for one of the first 200 911s made... and opened up the spigots and made extensive performance modifications to increase the horsepower by 60% or so... so that making the engine appear original would require installing sand cast chain boxes. center-lube cams and Solexes... but it was still an altered engine.

With all the period correct parts (provided but not installed), what value "hit" would this engine take over another decent-running 64 engine?

Asking for a friend... :-)