That is all very good info; thanks. And now I see why this is in the 'Edelbrock heads' thread.
In my view.... if you don't want to put in pistons again when you go the the Edelbrock heads, then I would push towards some flat-top pistons. The 574's are open chamber heads and the Edelbrocks are closed chamber heads.
For pump gas, and the Edelbrocks AND with 93 octane pump gas and a lot of cruising, I personally would be staying at 10:1 to 10.5:1 SCR; this limit, and the closed chamber Edelbrock heads, point to flat tops, not domed pistons.
The higher SCR helps make useful torque at lower RPM's and widens the torque curve down low, all which makes day-to-day cruising fun a lot better. You can achieve the higher SCR with either engine, so your direction with the domes was basically right for the 574 open heads but they would not work long term with the Edelbrock heads as you would hit the heads or just have too high a CR for pump gas without going to super thick head gaskets or a huge cam which would suck at low RPM cruise.
Flat tops can be KB Hypereutectics (lightweight) or a variety of forged (Ross, Icon, etc.) or cast Sealed power types. The forged are the most durable. The ligher 'hypers' generally make it necessary to rebalance the crank, but you may be doing that anyway, and lighter parts takes some loading and stress off of the lower end.
The downside of the flat tops will make the CR lower for the 574 open chamber heads. Your rear gear is higher so that helps, but you can make up for it more by putting in smaller cam and just letting the revs and top end HP be a bit more limited 'til you change to the AL heads. (Though with your good breathing intake and exhuast parts, it will still rev pretty darned well.) Or, put in a higher stall TC BTW, rev it more when you start off.
BTW, I have not run any DCR calculations at this point with the flat-tops, 574 heads, and various cams to see where that ends up.
And one more thought: You might be able to get some 'flat domed' pistons (the KB243 hypers is one example) that will help keep the CR up with the 574 heads, and then take them out and machine the tops down some when you go to the Edelbrocks and have good SCR in both cases. Some research would be needed on the piston head thickness but I suspect it will work. And you can always vary the head gasket thickness, starting with thinner ones with the 574 head, and going thicker with the Edelbrocks.
If you select the parts right, then the Edelbrock setup will end up with what is called quench, which helps fight detonation and improves combustion efficiency.
Sorry if that is a lot of rambling info! Your planned change in heads got my head to spinning....LOL. It is an interesting problem.