Hey Austin,
I personally like all of them, each have their good points, each have their bad. Personally, I love the RB engines, BUT if i was a younger person(which i happen to be) and if I didnt have a kick as highpaying job (which I dont have yet) then I would avoid anything that wasn't available in the states. The 1Jz might still be an option because of its sister engine being available in the lexus and toyota cars. I'm not sure what all is shared amongst them, so I cannot help you there. Which one is more common(or had more production) the 7m or 1jz? that might be a determining factor. I know you like to drive your cars, and you do have a daily driver so your not Reliant on the Zed, BUT do you want to wait for ever to get parts? and then pay more than usual? what's the cost on the RB's now a days? The last rumor I heard was that supplies are now drying up and the market prices are starting to reflect that. I could be very wrong though as I don't have any RB experience, merely hearsay and conjecture.
are you ditching the SDS? Can I ask why, and how much you want for it 8)!
I love the idea of a 1JZ, or RB powered Z, and would probably lean toward the 1JZ. Have you looked into buying a NA 2JZ and building it for boost? that might be a cheaper option in the long run......maybe?