Using LX (New Charger/Magnum/300) Wheels on a 74 Dart

My 1974 Dart Swinger came with a set of Ford ( :angry7: ) Magnum 500 style wheels on it and some rather old tires.
Next summer I am going to be purchasing some new tires, out of necessity, and I'd like to upgrade the rims at the same time.
I've always been a big fan of the new LX rims on the A-Bodies.
I saw several cars at Carlisle with them and its a look I'd love to do to my Dart.

During the winter months (downtime) I'll be on the lookout for a set of rims in good shape for a good price.
They are out there, its just a matter of finding them.

However, what I'm not entirely sure about is how people have been fitting them on their cars.
I've got the 4.5'' bolt pattern, and those wheels are a 4.5'' bolt pattern, but I didn't think the offset was correct to work on a stock Dart.
So if it isn't what do I need to make them work?
I don't know a whole lot about offset or backspacing, so take it easy on me. :D

Also, if I do go with the 18'' wheels, what size tire should I run?
I've got air shocks in the back, and new shocks in the front, and I don't want any rubbing at all, under any circumstances.