What kind of intake manifold I need to carburate my 350 TBI. (I do not have the ECM and wiring harness). I plan to run the engine with a stock Quadrajet that I have. Also, for the ignintion, more than a HEI distributor, what shoul I need?????

any older stock GM 4bbl intake or a aftermarket spreadbore intake for a SBC. Personally I would look into getting the harness and ECM for the TBI.....your going to want it later anyway.

The older SBC intakes will not work on the 87 and up because the two center bolts are at the wrong angle. You could try redrilling them to the proper angle but a better choice would be to get a manifold with the proper holes in the first place. I think Edlebrock is the only company that makes a manifold to convert the FI engines to a Carb bot you could try Holly or WeiandThe Edlebrock part number is EDL-2104

Not what I'd do. Hell man, TBI junk is dime o dozen. Get the right stuff and for what it would cost for conversion new stuff, you'd have a working TBI.

I'm a moderator on a Camaro Firebird TBI board. You're all more than welcome to come ask questions. We have a couple of non Camaro Firebird people that get help too. There is also a board for to help you custom do PROM burning.
http://www.thirdgen.org/techbb2/forumdisplay.php?forumid=17