They ARE too much for your intentions. ( the heads)With very little convertor( a big key to a “ racy” 318) and 3.55 gears sounds like you are just kinda looking for a street cruiser with some punch.
The kind of heads Fast68 above mentioned are a good way to go
I say all this as a guy who raced a 3400 pound pump gas 30 over 318 that ran mid 11’s with iron heads. Pretty trick little piece .That took a 5,000 convertor