Your E-type's performance modifications to date appear to be inside the engine bay, so the car presumably remains competitive for JCNA Regional and North American awards in the Driven Division of concours competition. (The engine bay is not judged in the Driven Division.) The mods you mention make sense for a driver car, and they can be reversed.

Converting the bonnet to closed headlights would make concours competition problematic. More importantly, such a modification, presumably for cosmetic reasons, could not be easily reversed. I would discourage any major cosmetic modifications to an E-type. They can disrupt the classic style of an E-type and even turn it into a jarring hybrid by mixing and matching major visible features of two different E-type series.

Would you be ruining the car? No Would this be sacrilegious? Yes