If you have a .528 cam with a 1.5 rocker and that becomes a .563 cam with a 1.6 rocker. How would that compare to a .563 cam with a 1.5 as far as valve-train load, etc. Would it be better to have the smaller cam and a 1.6 rocker, or larger cam and a 1.5 rocker?

For a bracket type engine it probably doesn't matter. On a high speed race engine it might matter a lot. There is no answer to your question without having a ton more information since it is all going to depend on the lobe profile and the rigidity of the valvetrain and how well the port works and a bunch of other things. But if you're just talking about a modest performance back yard build then you'll most likely never notice the difference.

Like Andy said, it depends on cam lobe profile, and other factors.

There are a lot of trade-offs when working with the original block and head dimensions.
Most of the high lift cams are designed for higher ratio rocker arms, because the cams lobe lift (lobe height) has to fit through the cam tunnel, and you can only reduce the base circle of the cam so much before the cam torsional twist throws the other cylinders timing off (although it can be compensated for to a point.)

For the most part, going from 1.5:1 to a 1.6:1 is pretty easy, and general work with no to little changes. Need to check pushrod clearance around the heads, valve spring coil bind, and piston to valve clearance. This assumes you are using pushrods of the correct length and strength (Thickness, material, etc.)

With the rockers themselves, I think around 1.7:1 ratio is about it using the factory rocker shaft size and location.
If you want higher ratio, and valve lifts of 0.800+, you should goto a paired shaft rocker system that re-locates the rocker shaft location. Not to mention the valve spring pressures with these aggressive cams will be hard to retain (keep bolted to the head) a stock rocker shaft system with the five hold down bolts.

The 1.6:1 rocker arm increases the spring tension on the pushrod and tappet at any point of lift (except valve closed) by 6.7%. If your pushrod is marginal, don't do this.

Camshaft is the Mopar Performance .528 solid. Have Comp cams .080 push rods. Edelbrock RPM heads. Currently using 273 rockers, but was thinking of switching to a 1.6 rocker.

Go for it if you have the parts. No problem with trying stuff to see if it works. Just don't be surprised if nothing happens. A lot of the time you won't see any results from a change like that. You might want to read this article. I spent several thousand dollars trying different rocker arms and found nothing. Zero, zilch, nada. Been there, done that, and have the hole in my wallet to prove it.

https://www.hotrod.com/articles/trying-find-extra-power-rocker-arm-testing/

I think the MP 528 is a good candidate for 1.6 rockers in many applications.

What ever you end up going with, you'll want to be sure that the geometry is pretty close to correct. You could end up losing some of the lift that you would have gained with the 1.6's and have an unstable valve train.....plus, there is a chance the new rockers could hit the springs if you have 1.54" ones. mine did. (Indy ez heads)

If you go to the B3 Racing site it explains it better than I could.....and you'll likely need new pushrods if you go that route.

I use their rocker correction kit currently with 1.6 intakes and I compared lift with and without it, and while I don't recall exactly the difference now, it was significant. (something like .015-.020?) I don't think I'd use the B3 setup with roller cam spring pressures, but on a flat tappet it seems more than stable enough.

Stock type rockers are pretty good geometry wise.

I agree, the 528 would be a good candidate to speed up a bit with more ratio. 1.60 rockers might be worth 10 hp on the dyno.

The advantage of the 1.6 ratio rocker would be that the cam lobe can remain less aggresive, thus the remainder of the valvetrain taking a bit less beating.

Simply put, to get the higher lift on lobe design alone it will have to rely on steeper ramps. When you start looking at that whole "area under the curve" mapping I would suspect that a higher lift lobe would have less resulting area (at the valve) than the lobe meant for the lower lift. After all, the only way for it to match the higher lift would be to make up the mechanical ratio advantage of the 1.6 rocker by building in more area at lobe, which would presumably increase cam duration, etc. etc...end result being you are no longer talking the same cam specs...again, all of this if very general though!

Just what I have learned over the years...my current W2 build made we go from MP 1.5 rocker to Hardland Sharp 1.6 pieces.

In my current ride (360 motor, heavily ported 596 castings) I did go from 1.5 to 1.6 on a Hughes HE3844AL hydraulic flat tappet cam (.536/.540 lift @ 1.5, and .571/.576 lift @ 1.6). Not a big cam by any means, but this is a street vehicle, so plenty enough. The butt-meter told me the motor felt more responsive, the idle sound certainly changed, it had more "crisp" to it...