@A_Blind_Reefer is spot on! You will want the intensity to be pretty maxed out unless you run supplement lighting in front and back.
Even the BRS video stated that over an area 40x20 at 18” depth you will only be averaging less than 100 PAR since the 75g is deeper. Also, those numbers are directly under the light pucks. The outer edges barely saw 70PAR, even less. For example, I had a 40 breeder 36x18x18. I was running two Kessil a360x at 75% just to get 200 on sandbed directly under the lights. The ends of the tank and front/back was probably 100-125. It wasn’t until I added Meridian edge bars front/back that I was able to get an even 200-225 everywhere on the sandbed.
I love Kessil for the color and shimmer, but you need more than what is recommended due to them being more of a spot light. The spread and PAR are quite weak. Had I not added the edge bars, I was going to put a third a360x over the 40 to reduce shadows and have better blanket coverage.
Your tank is longer and deeper meaning you will be hard pressed to keep corals at the ends of your tank and close to front/back panels.
In my current tank, my zoas and mushrooms get 225-250 PAR. Acans and favia 150-175. My torches, hammers, frogspawn and gonis average 300. People way under estimate PAR requirements. The vendors/sellers recommends certain PAR, always on the low side, so people hopefully don’t throw a blasto on the highest point in the tank and complain when it fries. I digress. However, you can look at tanks on this site where people with mixed tanks run higher PAR. For example,
@JGT has a simply amazing mixed reef and is running some serious lighting.
@Troylee grows his torches in 500+ PAR, he even did this under halide before going Meridians.