I had issues with my 440 in the Texas Summer heat. I said to hell with that and went all through the car to make sure I wouldn't have issues stuck in traffic on 100 degree days or when I went to Cruisin' the Coast in Mississippi. It's hot as hell there in October.
Sometimes we can over think issues like this. It shouldn't be too complicated to figure out though. Is this a new issue or has it been ongoing? Maybe you just got or built this car?
Check your timing. A little water wetter won't hurt but it's not a cure-all if you have an actual issue.
You may have to dig into it and see what you find. Might want to replace your thermostat. Cheap enough to do. Get one that, when it fails, it sticks open. You might want to run a 180, I have friends who run 160 and I run a 160, and a couple guys I know don't run one at all. With whatever temp you choose, you're really just saying I don't want my cooling system to work until it gets to that temp. If you choose a hot one, your cooling system would have to be working amazingly well to keep it around that temp. Probably not gonna happen.
Might be as simple as needing your rad rodded out at a radiator shop or it might be better to replace it. Just got to check it out and see if it might be full of deposits. If you replace it, you don't need to go crazy on a 4 row polished aluminum one. 2 or 3 row factory rads are fine. Cleanliness is important. Doesn't take much in the way of deposits to inhibit your rad's performance.
I run a 7 blade factory fan with a heavy duty fan clutch. Factory fan shroud. Factory stuff worked back then, should still work now, unless you've got some crazy build.
One thing that gets overlooked and I've learned can really help is to make sure the gaps between the rad and core support are sealed up. It's probably not going to make a gigantic impact but it does help. If you have gaps, well you'll pull air around the rad instead of through it. I found some foam weather stripping and sealed all those gaps up. There was a gap on my car that was too big for this foam and so I used a piece of angled aluminum on that area (because I have one of those fancy aluminum radiators). There's a piece of weatherstrip on my 72's hood that seals down across the top of the core support. Stuff like this can easily be missing and affect cooling in extreme temps.
Another thing is air. If you get an air bubble trapped, it'll run hot on you. I bought myself one of those spill-free funnels that allows you to get all the air out without **** going everywhere. I love that thing. I'll link one like it.
https://www.summitracing.com/parts/lil-24680?seid=srese2&cm_mmc=pla-msn-_-shopping-_-srese2-_-lisle
I kept my factory gauge but I wanted to know exactly, at all times, what my temp is so I installed a mechanical temp gauge as well. My car runs 160 when it's cool out, but most of the time it's floating just below 180. In the hottest temps, it MIGHT get to 185 in stopped traffic. If I ever see it get above that, I know I am having an issue and it gives me more of a chance to figure it out as opposed to having an actual overheating problem. I actually installed the highest power flex-a-lite pusher fan on the front of my rad for just such an emergency. So far, that has been overkill because I never use the thing but it's there just in case.
When I was at Cruisin' the Coast I saw cars dropping like flies. Cars pulling in to shows hot as hell. Sitting on the side of the road overheated. I sat in the lines all week without a worry in the world. THAT was a good feeling.
You'll get it figured out.