I am a similar build to you but keep more of my weight in my stomach so a slightly smaller chest, somewhere around 54.
I got the 3x Truspec and it fits fine, a little snug in the stomach when I sit down though.
As I said, my chest is smaller, stomach a bit bigger and I would say, 4-5 inches to spare in the chest. I can stick my hand in sideways without much resistance.
I would say a 3x truspec should be just big enough, though it might be a bit tight.
As for the belt, I got 2, though I did something a bit different with them. Instead of sizing them separately I kind of combined them.
I took one belt and extended it to the maximum length, then took the other and over shortened it, so that the underside was longer than the over side.
Then I combined them so that the lower side connected to the... you know what I'll just show you.
https://imgur.com/a/SzjXK Larger Image in the link and a 2nd with a closer view.
Yeah, basically that, it brings the connection towards the side so that you can hang the gloves over it and hide it.
I use one of the belt fobs to keep hook from slipping when not wearing it and then a bit of string or clear tape on the "buckle" just so it doesn't fall apart when putting it on.