SBC in my Sebring has no oil dipstick installed.

Is this a common set up? Is it difficult to install one?

No it's not common.  You really need a way to check the oil level.

You need to determine which side the dipstick boss is on.  If your engine is older than about 1982, it will be on the driver side.  After 1982 or so, they were on the passenger side.  GM sold some universal replacement engines that had provisions for dipsticks on both sides, so that the engine could be installed in any year.

The stock driver side dipstick tube just slips into the block with snug fit.  The passenger side tube is retained with a bolt into a threaded hole on the side of the block.

There are also aftermarket dipsticks by street rod suppliers.  Lokar makes several and they are flexable so that they can be mounted several ways.

Also, if you have a stock oil pan, it will hold 4 quarts in the pan to the full mark on the stick.  The filter will take approx. 1 more quart depending on the actual filter you have. Some are larger than others.  If you have an aftermarket oil pan, you're on your own as to capacity.  There were some stock performance pans that held 6 quarts, but they are fairly rare.

Determine the type of block you have and check back.

Thanks for the reply. Much appreciated and I will begin checking out the year the 350 was manufactured and go from there.