Rotary vs rice burner

Can someone please tell me the advantageous and disadvantages of a rotary moter over the typical four cylinder rice burners you see on tv.
i have just acquired a 73 opel gt with a junk motor and im torn on what to put in it.

Rotary's are able to be significantly smaller but put out a ton of HP. With that being said, they are extremely unreliable, usually have oil leaks and other problems, they are also quite tidious to tend for.

Rotaries aren't "extremely unreliable", they just require more maintenance in order to stay reliable.