fisher stereo

Bingo.
https://www.amazon.com/dp/B08FG4NW4F/ref=cm_sw_r_apan_glt_fabc_JG7VVTD3P3GTF5X2XEZC
They look good to me.
I doubt there is room on the back of the receiver to do any better. And you shouldn’t alter vintage stuff anyway.

Keep in mind that the older stereo compacts with RCA jacks for the speakers were rarely that powerful.  Not sure what speakers you were planning to use, but they would need to be fairly efficient.  

Good luck.  I had a SONY HP161 compact in HS & college that I just loved.  

Rich 

Thank you for all your help. I will take a look at the amazon speaker cables. That would seem like a much easier solution. The sound on the Fisher was good for a while but the original speakers gave out too quickly.My dad never bothered to replace them at the time so we had just bought another stereo later on. I didnt know that  he kept the Fisher and he  just unboxed it recently. It would be nice to use it again as a secondary stereo and one that he is familiar with.

Hate to be a downer but…as rar1 suggested, I’d be shocked if that item has as much as 5W @ 10% THD. Those ‘70s compact systems were not all that good. Don’t expect too much. KLH made pretty good ones, but Fisher, not so much. 

https://www.analogalley.com/osccart/product_info.php?products_id=1368

...spend another 14$ for the pdf of the original owners' manual, and it might give a hint as to what its' specs really were (maybe)....*S*

Sometimes things are worth more than their specs or the relative worth to others....;)

Enjoy, even if only for memories and for Dad.

Even crustycoot should give that a nod.....