I have a line on a Edelbrock Q-jet from a seller on Craigslist.  Says there are about 10K miles on the carb.  Same seller also has a set of Vortec heads and GMPP low-rise manifold that I am seriously considering and he wants to sell everything together.  Is the Edelbrock worth it, though?  I think if you itemize the package he'd be looking to get $150 to $200 out of the carb.  Were there a gajillion variations of these like the originals, or were they a "few sizes fit all"?   Since my car is a '76 I have an emissions carb (# starts with a "17" instead of "7")  and I've heard those are definitely more challenging to mod for performance than the pre-'75 carbs.  Would the Edelbrock make that easier?  It has an integral electric choke (good since the vortec manifold does not have a choke stove provision) but it also has some kind of solenoid on the throttle (idle stop solenoid??) that mine does not have.  Would I need that?  I guess both that and the choke would hook up to an ignition-on 12V source?  Would welcome any of your opinions - but I do have strong desire to keep a Q-Jet on there.   My proposed engine: 355 w/ vortec heads, approx. 9.5:1 comp, medium sized cam like a Comp 268.  Pic of the carb:

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My guess is that the Edelbrock version of the Q-jet would be excellent for you.  There's certainly a possibility the carb might require re-jetting for your engine as every cam and head combination is somewhat different.  Being realistic, your emissions era Q-jet would require the same to reach its best potential considering the intake and head change you're contemplating.

Edelbrock Q-jet's use "truck" metering rods in them. Which is not good for any high rpm range. They cause a lean condition up a little pass 5000 rpms. I had this problem with one those Edelbrock units. A guy named "Lars" on the other forum clued me in on these carbs. He is one of the best Q-jet guys out there. To bad I wasn't doing my fuel injection conversion yet. I would sell you my Q-jet that was done up for my engine by SMI Inductions. It would probably drop right on with minimal tuning. 

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GEN III 5.7L "LS6" Engine swap
TKO500 5 spd.

I have a Quadrajet with the 17 prefix on the 406 in my Nova. It was reworked by a guy in Phoenix to perform with the specs of my motor. Some passages were enlarged in the idle circuits, jets and rods changed and the secondary side adjusted to fully open. It is feeding about 450 horsepower with no problems. The air choke cover was replaced with an electric cover, they are the same size so it was a bolt on.
My advice would be to have your present carb configured to your engine, in essence it should not cost any more to modify yours than buying the Edelbrock and the Edelbrock will probably need to be tweaked somewhat to run on your engine.

Thanks guys.  Good to know - why spend more $$ on a carb that may need as much as work as the one I already got!  Sarge, what's your time frame for doing the conversion?  It'll be a few months before I'm ready to get this thing on the road....

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Dave, I'm not quite sure yet. I just plunked down some big coin on these '69 style side pipes and more $$ for structural reinforcement goodies for our 600+hp GTO. I will be visiting with my "computer tuner" on putting together a F.I. system for the vette for relatively cheap... so he says. So if I can do the conversion in the next couple months I'll let you know and see if you are still interested in the carb.

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GEN III 5.7L "LS6" Engine swap
TKO500 5 spd.

Keep in mind the Edelbrock q-jet IS the old Rochester q-jet.  When Rochester quit making them, Edelbrock started making them to meet a continuing need (and make money, can't fault that).  Granted as already stated, there are many different configurations, and many different ways to tune them.