My Penn 710 greenie I have has a green spool on it - it isn't metal. I have always used mono on it and if I were going to use a "super line" it would be Fireline on one of the gold anodized aluminum spools .
I would be a little worried about splitting/crushing the spool w/ packed on PowerPro on a green "plastics" spool. I don't see many of those spools for sale.
MikeP would be able to tell us what it is made of.
Did Penn make silver anodized spools for the 710 or 712 greenies? I never owned a 712 greenie and the 710 I got from some one else back around 1985 (the other person had it for a while before that).
I know the small 716 & 714 greenies had silver anodized spools.