My experience is that if it's not original, then it's not worth money. So, restoring it to what it would have looked like when new will be worth a lot less than making a red RS/SS with Z/28 stripes, 20"+ aluminum rims, and a 383, 454, or 502 crate motor. If you plan on showing the car, the orginal treatment wouldn't impress very many -- the bastardized monstrocity will win you trophies.
It all comes down to your preference and your plans. If you really are building to sell, then it will be much tougher to get value out of the properly restored 327/210 non-SS car than building a "never existed from the factory" combo of exotic features, modern conveniences, bling, and lots of power.