Fins for 70s single fin shortboard

It’s a 6’6 kinda gerry lopez shape with a thicker shorter fin than im used to on the log. I feel like if i put a new fin on it will drive more. It would also have to be a fin that has the screw slot in the back because its the retro style with the leash attached to the screw. Any ideas?

Check out Fins Unlimited. 

What you probably have in there is a Brewer style fin.

 

get a brewer (FU) or parrish (true ames)

those were the fins back used  in the day

some pics below including a gerry lopez fin from rainbow

 





what about a log fin? got a 9" and almost brought it out today but was feeling insecure about it…more drive and speed but less turning capabilities is what im guessing…useless?

Just try it if you don’t like it take it out.