I would not evene go near an Express with 175's. My F225's cruise at 28mph, DF175's would put you way down there, probably 24mph if your lucky. My F225's top out arounbd 43mph....DF175's would not even touch 40, maybe 38-39 if your lucky and propped out right, in today's market that is slow and not appealing. The 265 Express is a big boat for it's size, and in a rough sea you need the power to stay on plane at slower speeds, 175's will put you off plane too soon and kick your butt. Also, the hull likes to run, and run fast, in a close 2-4ft chop, I put the throttles down, trim her out right and run 33-35mph and fly by everyone else out there....underpowering this hull will make it ride like crap and lose its sweet spot both on ride and speed. For the very little in fuel savings, it would be a HORRIBLE decision to underpower this hull. I think 200HPDI's or F225's are the perfect match. Honestly, if you put DF175's on the boat you will have an extremely hard time down the road reselling the boat...you will be the only boat ever with them and everyone looking will wonder why no others...whats wrong with this one, you will have to find someone very inexperienced and unknowledgeable to buy it. I like the Suzuki engines, but a 175 is underpowered. Your talking about maybe 60lbs per engine between most 225's and the suzuki 175, a total of 120lb, l;ess then one adult at the transom. Stand back there in the well and see if your scuppers are under water. You may not need an adjustment, mine was a 2002 with 4strokes from the factory and my scuppers ride high enough, if you are closer to a 2000 hull, you might. Somewhere between that time they adjusted the height.
My advice would be stick with 200hp and above, but honestly a 225 will be a good match, when going from a 2 stroke to a 4 stroke, never go down in power, stay the same or go up, 4 strokes don't have the pep of a 2 stroke if underpowered. My F225's jump on plane and have plenty of power.
As for the Parker, it is a totally different beast, different hull, it planes out differently and requires less hp to run at certain speeds, it has less deadrise and therefore gets more lift at the transom, and will plane out with less power. Compared to the 265, a Parker will rattle your teeth out unless you get the deep v version, but those with deep V's usually have 200's or more hp. A deep v parker was one of our choices when we bought, and after a sea trial there was no comparison.