I too would recommend ordering the 7660 with your case and add one or two centimeters to the recommended cable lenght suggested on the densium website. Don't forget overteks powersupply comes without basic c13 power cord to plug into your wall outlets, so order your own. You can opt for a fan swap in the psu and Overtek does a killer job at it (check his youtube), but i'd only go for it if you reckon you'll be using a full 3 to 400 watts for long stretches of time. To be honest my system with ryzen 3600 and rx 6600xt doesn't even use enough watts on full blast to trigger the flexatx fan to start, so it's quiet as can be stock.
I bought the z-39 but it works better with a noctua 92mm fan.. So I also bought the l9a cooler. Since I prefer mounting with a backplate (z-39 doesn't have any) I installed the noctua l9a and very happy with performance. Another cooler you could try (but also wants a noctua 92x14 mm fan to be quiet) is the axp-90 x36
Also, buy the riser through Densium to be sure you get the right angles.