VECTOR: Probably a stupid question...

Picked up a non-working Star Wars the other day, have already found a faulty
inverter at 1N but suspect there's more faulty parts to be found!

 

My question is this.  can I replace the 74S04N at 1N with a 74LS04 or a
7404N?  Normally I can find a matching part on my parts pile but I can't
find one of these anywhere!  I'm suspecting the answer is no as I'm assuming
the S to mean it's fast (?)

 

Any help very much appreciated.

 

Thank you.

 

Pobster