The opening in the upper is 70mm that is enough for anything you can really do with a stock block. I'd just get a 70mm and not waste the money on getting the upper ported. I can't say enough about Tom Moss doing your lower though. It might be more than $150 but even if it is, the ported Cobra lower is a MUCH better option than a Edel/TFS/Holley etc.
Tmoss ported a GT40 lower for me and it is tits. His ported lowers flow 250 cfm and the uppers flow more than that in stock form(another reason to not to bother with 75mm). The 250cfm tmoss GT40 intakes will keep up with Twedges/165s/Performers/Systemax etc... heads and the low end with that intake is monstrous. I have the much maligned Edelbrock RPM heads and everyone told me it'd be a pig down low. Well I have a Tmoss ported lower on there and it sure as hell feels strong below 3,000 and it SCREAMS above that up to about 6,500ish.
A great option if you don't want to have to wait for your intake to go out, be ported and come back is to go find an explorer/mountaineer lower(any explorer/mountaineer 5.0 lower works the same with 94/95 cars so don't worry about 1st or 2nd gen or EGR holes or anything like that) and have Tom port that out so you can bolt on and go as soon as you get your car apart. They all flow the same stock and they all flow 250ish cfm when Tom gets done with them. Then sell your OEM lower to recoup some of the money you spent on the explorer lower and portwork.
Tom ported intake happily perched atop some Edels.