I have a 6.3 v filament transformer for the crt on my philco set , but even at 117v pri power ,to the transformer, the sec voltage is between 7-8v, to the tube. Should I wire a resistor or pot to control the voltage and keep it around 6.3v ?

Your transformer is OK and working normally. When you have the filament load on it, it should drop to around the proper voltage.