Make sure you check out the coolant passages for pitting and the intake gasket surfaces especially around the coolant passages. As Carl mentioned the threaded areas should be inspected. Nice manifold if it's in nice shape.
To get a true idea of what that 3933163 is worth, you'll need to look at the casting dates...that manifold was sold over the counter until quite recently. If you pay around $150 you'll have no where to go but up in value! That one looks like it may be newer. If the numbers show it to be for a rarer date of car it could be worth $400++
You can use that manifold on your oval heads, but i'd say you'll be giving up a litttle bit of power compared to the two aftermarket oval intakes. If you like the oem look, the bit of power you might lose wouldn't be too noticeable. People used to put those intakes on oval heads a long time ago when aftermarket or oem ovals were not as available and didnt flow as well...
The stealth is a great intake, may flow too much for your current set up, but does give you room to grow your engine (especially if you have the intake already)... if you own it, and don't mind the aftermarket look (vs. the 163), then you have a great setup!
The performer is also a good intake for your setup...(assuming you are keeping it under 6000rpm?)
I wouldn't be too worried about the plenum divider being cut out on any of those intakes, on a larger hp and rpm engine you would notice an increase by having the divider cut out...
A decent street carb with good manners would be a holley street avenger 770, you can buy a reman one direct from holley (on ebay) with a warranty for the same price as used ones...
before jumping on this GM intake: 1. Verify all the threaded bolt holes still have their threads. There's only 9 to look at, but if they are stripped it greatly reduces the value of the intake. I see the 2 threaded bolt holes for the thermostat housing have studs in them, not sure if you'll be able to check those.
2. Take a good look at the aluminum around the heater hose outlet by the #2 cylinder. These have a habit of breaking off, so look for any signs of cracking.
3. And I see a long nipple on the front for the by-pass hose. Will you be able to get a hose on to that and bend it down to the water pump? If not, you'll have to remove the nipple, which are usually really stuck in there.
