Sorry, maybe I should have been more clear, I watched some of the video comparisons of his ported explorer to a systemax II. And it would appear the porter is using the comparison of the two as a selling point.Now wait, you are endorsing an intake good on a 347, yet questioning if the heads need more intake and TB than the one built for the 302 the OP is using? It sounds like a up combination suggestion to me.
While I don't necessarily disagree with some port matching of the explorer lower to the heads, I really wouldn't want to pay for it. And i certainly wouldn't have it opened up to 75mm. Hell, an RPMII only comes prepared to accept a 70mm and i've seen that intake make 360rwhp all motor on a stock shortblock.
For the OP, I really don't mind the E cam, online guys hate it, but i've seen it run pretty well. What i would be more concerned about is factory explorer valve springs. I know what it's like to float valves and it's really not if, it's when.
The gt40 iron setup is a budget build (hence why i don't like investing more money in it, if someone has more money, they might as well use better parts), so a budget cam like an E isn't a terrible choice.