(1) The Q-jet pictured is not from a 1st gen. It's a later model. Has the hot air choke and a different choke linkage, plus one of the big "smokestack" vents which Pontiac used form '71-'79. The intake is also from a later '70's engine, because it has the big EGR valve coming out the side, just below the carb. The most common engines which used these intakes and carbs were the '75-'78' 400's, with a 500557 or 568557 casting number block and 6x casting heads. I believe I can just barely make out a 6x on the head pictured in your 1st post.

(2) You can make a positive ID on the engine by locating three different numbers. (#1) The block casting number which is located on a pad, below the rear end of the head, on the passenger side--just behind #8 cylinder. (#2) The block date code, which is just behind and to the side of the dist hole. The 1st digit is the month, the next 2 digits are the day of the month, and the last digit is the last digit of the year the block was cast. (#3) The engine code, which is just under the passenger side head, on the front of the block. Most of these codes have 2 digits--some have 3. It could be something like a YX, or a WT or something similar.

Then, armed with these numbers and codes, you can look 'em up in one or more of several online Pontiac engine ID sites. Some sites have the wrong info. But most sites have most of the info correct. The Wallace site has a good engine ID page. You can enter the info you know about the engine and it will give you the possibilities of which engine you have, based on the info given. The more info you enter, the more precise the results will be. So, get the numbers and codes I mentioned and plug 'em into the blanks and see what turns up.

http://www.wallaceracing.com/enginesearch4.htm

You can't always make a positive ID with just the engine code alone, because Pontiac used the same code on different engines. For example, the same 2-letter code may have been used on a 301, 350, 400, and 455, but only one of these in a particular model year.

http://www.pontiacpower.net/engcode01.html

The most common 400 block casting numbers were 481988 from '71 thru early '75, 500557 from late '75-'76, 568557 from sometime in '77 thru '78, and XX481988 for the W-72 400's in '78 and '79. The last 400 blocks were actually cast in '77. Can't find where anyone has run across a date code later than about Nov of '77.

(3) The heads that are on your motor may not be what came on the motor. But you can get the casting code off them and check 'em out on some of the Pontiac head ID charts.

http://ronspontiacpage.com/reference-pages/stockheadspecs.htm

http://www.classicpontiac.org/FAQ.asp?myPage=V8HeadInfo

http://www.bassettracing.cz28.com/custom3.html

(4) Dexron is OK. Back in the old days, we were told to use Type F, because it was supposed to withstand just a bit more heat than Dexron. But I don't think it was really that much better.