You're welcome. It is my pleasure to be able to help. I think we've all got a passion for the cars here and to see you replicate them in a smaller scale with accurate details is fascinating and relatively awe inspiring. I'm particularly enjoying the fact that I'm the one making suggestions and you're the one doing all the hard work!
With regard to the interior panels, are they deluxe rather than standard panels in the '69 GMP model? Mine are all boxed up. Standard panels for all three years are different, to varying degrees. I'm not sure how you do all this casting of wheels, panels and/or tires. That would be a fascinating side story in itself.
P.S. Yes, power steering was used on Ron Bucknum's car at Michigan but not the larger tires (to my knowledge).