Agreed. Just make sure it is not a Poly 318 and it is indeed at least an LA engine. (Or Magnum)
$300 is fine it if is in excellent condition but not for well used.
As far as actual year is concerned? None are any better in general to get over another BUT, new (or lower mileage) is better.
The Magnum engines are really well for the fuel injection does really well for longevity of the engine and it's cylinder wear. Just realize it oils through the pushrods and not through the block like an LA.
