It does not idle

[stetson man]

I used to know how to do this stuff, but I haven't worked on cars much beyond changeing oil and plugs for the past twenty plus years & boy I have forgotten a lot.
I've been searching the form for a similar problem, but haven't seen one yet, (I should know how to do this).
I got a new knee joint replaced in Feb. and have started working on my chevelle this summer.
Back ground:
I bought an 86 stock 305 in search of better mileage to replace a worn out non running 350 .
The engine came complete with the HEI distributor taken out and no carb.
I tried the original Q-jet from my car, but the accelerator pump leaked. Then I put a recently rebuilt Q-jet that I got from a friend, later learned was for a 454 (17080212).
The engine would not idle and reved at high teen RPMs.
I figured the jets were too big so I bought a second Q-jet that was originally purchased for a 73 chevelle, but had sat on the shelf for 3 years.
It also revs at high RPMs.
I’ve check for vacuum leaks, backed the idle screw off, as well as the adjusting the screw on the passenger side.
The engine starts easy, it just won’t idle.
I thought I had a carb problem, now I’m not sure where to look.
Anyone have a suggestion?
Thank you for any help.