a few magnum swap questions

I don't think a 74 Dart SE will ever be a real collectors car so I'm going to have fun with it. I'm pretty new to Mopar and I'm not sure about a lot of the little differences. (Like, what's the differences between the 2 door hardtop SE and the 1974 Dart Swinger?)

Anyway, my plan is to put carbed magnum 5.9 into it. Paint it and drive it. I already have a Professional Products air gap style intake that is drilled for both the LA and Magnum.

Are there years of magnums that are better then others? Are there heads I should be looking for?

I've read that the crank pully from the LA needs to be widened, how much? And how? Certain years have better motor mounts (spun?) What years have these mounts?

Thanks,
Hillbillybuddha