I think the 74-78 was going to have to be a separate project. If there needs to be threaded port for a vacuum switch, that kind of solidifies my fears. Not saying we won't do it but we have a lot to do with the earlier C bodies which, no offense, are more popular.
As far as painting an aluminum radiator goes, It's pretty basic;
1. dust with a metal etching primer and then use regular black OEM shine paint like factory did. Don't use a high temp paint! It will trap the heat in the radiator.
2. only paint the tanks. that's all you really see anyway.
I'm not sure when the switch was moved, it may be one of the 74 Imperial only issues... my 76 NYB doesn't have it.
And whatever do you mean by "more popular"???