I have a very similar build to your for my HTPC on my siganture in case you want to see some info, i have power consumptions and temps under watching a movie, etc.
I think your choice of the case is very good specially for having a mechancial hdd on the suspesion on the solo. I do have some suggestions though.
Add fans to the front, very low rpms, in my case i spin them around 300-400rpm and even under load i have very good temps (check my sig). Im using an intel motherboard, that allow the pwm fan to be spin down that low. My suggestion goes into soemthing similar, either intel motherboard or Asus that has fanxpert2. If you can find them in stock, Scythe Slipstream PWM SY1225SL12LM-P
are really good case fans, thier 300-1300rpm gives you a wide range of operation, very similar to my Kamaflex2 pwm that i use. If you go with Asus board with FanXpert2, you can also control 3pin fans, so you could go with fans Noiseblocker M12-S1
(expensive but very good fan, if you can control it) or Scythe Gentle Typhoon 800rpm
(very hard to get atm), both reviewed by SPCR, Fan Roundup #6: Scythe, Noiseblocker, Antec, Nexus, Thermalright
. Another alternative for fans, is the clasic Nexus Basic 120mm D12SL-12
, but keep in mind that you will need to undervolt it as its 1000rpm on 12V.
The seasonic G series is a great PSU, but it will spin from start, and the solo II has open the top, so the fan so its a opening for noise to get out, with this in mind, specially for you not to hear at least the psu i would go fanless or hybrid, Rosewill SilentNight-500 $140
, its totally fanless, 500W PSU, its a rebrand from sunflower 500w fanless, it was reviewed by SPCR recently and came out really well, Rosewill Silent Night 500 Platinum 80 PlusSeasonic 560W 80 Plus Gold ATX 12V/EPS 12V Power Supply - X-560 SS-560KM $115
- a hybrid PSU and fully modular, that will be passive under light load and active under heavy load, but still very quiet, i have been running a X660 for two years on my gaming rig and i never can hear it even under the load of a GTX580. Its very nice PSU for the money, its out of stock atm in amazon but you can preorder it and wait a couple of week for them to ship it, @ $115 i think its the best quiet PSU for the money for you. X400/X460 are more expensive.
With that said, i just did a build for a friend an Silverstone PS07 and it also has an open top, and did it with G550 and to me under light load i cant hear it, but its not on a noise free envoirement like watching movies etc. So its your call if you go with G series.
For me i cant stand intel coolers specially under load.... but each person is different in terms of what bothers them. In my HTPC build (on my sig) i used a Scythe Mugen3 which even under load of a very similar cpu than what you want, its stays under 60C even with the fan at 300rpm, so my suggestion is to get Thermalright HR-02 macho $43
, wonderful cooler for the money, check if solo has the 162mm clearance needed for the macho though, also read the SPCR review for more info, Thermalright HR-02 Macho Quiet/Fanless Cooler
. The fan included on the macho is very decent for me, specially at 700rpm is very quiet, but if you want more quiet then get another scythe slipstream pwm and use it at 300rpm it should be enough to cool down the 3220 easily, you might be able to go fanless if you add the frontal fan to the hdd cage as its in line with it.... again you will have to the testing and see how are the temps for you to decide if its viable.
I would recommend to go with Intel or Asus (only with fanXpert2), get one that has the 1st pcie slot as 1x, so the 16x pcie is the second, this will allow you to install large heatsinks like the HR02-Macho or even super big twin tower coolers like noctua NH-D14. (whatever you go check the clearance with the solo II).
If you follow the above, this imo is what going to end up as the biggest noise, so chose carefully what you go for, i went with fanless GTS450 and i strapped a 120mm fan to it (300rpm and its inaudible). In the past many have liked the MSI design on this cards, i never have tested them but you can search spcr forum for others opinion, MSI NVIDIA GeForce GTX 650 Ti
. As an option if you were to consider AMD, they also have 7790/7850 fanless models.