The one in the clamp. That's a multi?
I've followed a bunch of the guys at AK and they have been bumping up the cap at C2 to 100uf and even higher to tighten up the bass. Leave C1 at it's rated uf as the rectifier can't take the extra power. I'm a little nutz - I put a huge 330uf in that spot in my 175. That's a 6V6gt based amp and it significantly tightened up the bass. C2 is where the output transformers get their power, they haven't caught fire, yet.
There have been a lot of 9300 series amps showing up at AK. If I were you I would send a PM to GordonW and see what he recommends, he is the Maggie king, IMO. He hails from near Dalton, Ga. and is a super nice guy.
Here's a pic of the 175 before I put that 330uf cap up on top. Magnavox badge from the console I gutted. I'll have to take a pic with the 330uf mounted. I went with birds eye maple & padauk?.
That fiddleback maple that you used is great!