when you get a new intake gasket it comes with rubber gaskets included for the front and rear rails - throw the d*mn things away and don't try to use them.
Instead, use Permatex Ultra Cooper RTV and put a nice bead along the front and rear rails on the block and let it sit for 5 minutes or so before dropping the intake down. Don't forget a nice bead around the end ports of the heads which are the water jacket ports also. Also, when laying down the bead of RTV make sure you put a little extra amount right in the corner where the block rails join the ends of the heads, this is a common leak area.
To give you an idea of the Permatex RTV on the rails and the around the water jacket ports I have a few pictures on my website showing exactly this step when I was reassembling the L82 from my '78 here:
http://69.253.166.197/page1/page127/page133/page152/page152.html
The pictures on this page you want to look at are in the 2nd and 3rd rows and are titled "Intake manifold gasket". They show the main intake gaskets after placing them on the motor with gasket adhesive than the Permatex bead before setting the intake down
When laying down the RTV try to make it a nice continious bead rather than stopping and starting or it probably won't seal as well.
You want anice bead approx 1/8" thick. Too much is as bad as too little - too much and it will ooze out as you tighten up the intake and you need to realize that it will ooze out as much inside the lifter valley of the motor as it does on the outside of the block so if too much oozes out on the inside, it can break off and now you have big pieces of RTV floating arounf the inside of the motor......potentially blocking oil passages or getting caught up in the lifters. More is not better - use the correct amount of RTV when laying down your bead.
I won't argue Gerry's advice on the anti-sieze on the intake bolts but i've never had trouble remove intake bolts from my motors. What I do use on them though is a nice dab of permatex on the threads before inserting them in - this keeps oil from wicking up the threads and collecting on top of the intake during use.
Felpro is suppose to be an excellent gasket but I used their gaskets on my valve covers and had leaking like crazy so had to replace them. On my 'L82 I ended up just going to my local Chevy dealer and they had the stock intake gasket set for the motor in stock (it's really nothing more than a basic Chevy SB gasket set anyway), it cost less than thru the corvette specialty parts vendors, it's the actual GM part, and it works great.
When reinstalling the distributor, don't forget to use the new distributor gasket that also comes included with the intake gasket kit.
Have fun!
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