Does anyone know if it would mess up the valvetrain geometry?

 

Would 1.7's work with aftermarket heads and a cc305?

 

As long as you have quality components on the valvetrain, I wouldn't think that you would have any problems using 1.7rr with any heads or cam. As far as valvetrain geometry goes, I am not sure, but a couple of people have been running 1.7rrs for a while on their LT1s and I haven't heard any complaints yet from those people.
Also, I think that the CC305 with the 1.7rr would make for a good street setup for a 383. Good luck.