all of what u heard is correct.
there are multiple types of gt40 style intakes.
1) real gt40, offered first as ford motorsport only piece, not on anything but then on the 351 lightnings, this is the good one to get, tubular separate runners and looks sexy. it's what i use to this day even tho some will say it's ancient technology. only downside is the upper cannot be ported (but you dont need to with a smallblock anyways)
FYI, that cover with the pony sells for $300 alone sometimes. hard to get but not necessary...cosmetic only usually the whole intake is about $500
2) cobra intake, same lower as the "real" gt40 but with a cast upper. same specs, no tubular runners but the good lower. found as aftermarket and all 302 cobras
then there is the crappy gt40p from the explorers. they look a lot like cobra's
but the runners are much smaller and u need to tap for the temp sensor or oil sender 1 of the 2
what you want is a lower with a "-AA" suffix in part number by the cutout near the dizzy
The BA is .96"x1.65" and the AA is 1.00" x 1.80"
the metal issue is probably referring to the fact all the newer "cobra" intakes are made in china. hence crappier quality
i believe i covered whats important