Sorry...I missed this post of yours, and only just read it now.
Actually, the Impala had been modified with a Buick 455 cubic inch (7.4L) engine, along with a TH350 transmission. When we rebuilt the Impala, we went for the "correct" 1967 vintage 350 V8, with its proper transmission. Thus, whilst the '67 Impala isn't actually COMPLETELY stock (since it has some modified fittings) it is very CLOSE to stock. Which is what we were aiming for, to begin with.
Of course, one of the additional modifications will be the sound system. And of course, there will be NOTHING but classic rock which will be played from it
I've installed an absolutely monstrous system in the '65, and I'm very very pleased with it. An identical system is going to go into the '67, Insha Allah.
Another modification, are the 20 inch wheels with 295/40/20 tires. Some things just need to be different!
Thanks for the appreciative words.