If it is a green label Colt, it will have the large front take down pin, but standard hammer and trigger pins. If it is a newer blue label colt, it will have the standard front take down pin, but larger hammer and trigger pins.
Personally, I wouldn't buy anything without the absense of a flash hider, collapsing stock, bayonet lug, and all other evil features - simply because the gubmint' doesn't like them. If they don't want me to have them, it means they are good for something.
$800 isn't bad for a Colt that you've shot, handled and inspected yourself. Colts do hold their value well, and just the name brings $200 extra.
Do this, go around the web, to auction sites and dealers, and see what a comparible Colt rifle new goes for. Same stock, barrel...etc. Don't worry about flash hiders and what not, they no longer bring a premium now that the ban is gone. Just find a very similar configured Colt. That will give you an idea. Beyond that, you'd have too look up the serial number or model # to find out if it is a model no longer made or from a previous generation that might bring it some more value.