You don't need to block off the exhaust gas crossover since you're using Edelbrock heads. The E heads don't have the crossover in them so you're good to go. The Performer RPM intake should drop on there without any issues using a factory bathtub style intake gasket.

There is also the Mopar Peformance version of that intake. The MP intake is exactly the same except it has some cool lettering on the front that says MOPAR WEDGE. It costs a few bucks extra but the lettering was worth it for me. The MP unit doesn't seem to be very popular for some reason. I'll post a picture of the one I have since I think it looks cool.