XE268 to Voodoo 03 cam change?

IMO, not worth the trouble. I don't think you will notice a bit of difference. And I don't think
a swap to 1.6 rockers is a very cost effective upgrade either. Good aftermarket rockers aren't cheap and cheap aftermarket rockers aren't good. Unless you already have the 273 rockers, I wouldn't bother with those either. The factory stamped rocker is lighter and if your lifter preload is reasonable with them, I doubt that the adjustable rockers will really benefit you. Not knowing your present combo, there might be better, more cost effective areas to upgrade. Converter, carb, intake, electric fan, ignition recurve, fresh air induction, etc?