All long hood cars are collectable.
That said: The last 70-71 car we did with a 2.2 opted to go the exchange route.
He kept his stock 2.2 (matching # engine) and we built a 2.7 RS spec w/Solex cams to install in it's place. The engine utilized the Zenith carbs and original looking ancillary components so the engine looks very stock.
Fun car to drive and yet still very collectable.
