572 RB Street motor advice?

I'd use the Trick Flow 270 heads. You could also use an Indy head but the Trick Flow heads will make plenty of power and they are nicely finished right out of the box. You can order the Trick Flow heads with a hyd roller cam valve spring and get them shipped ready to bolt on direct from Summit. You can't do that with the Indy stuff.
I'd also use a dual Sniper setup rather than carbs. Holley sells a dual Sniper kit now but it won't be a bolt on for the cross ram. You'll have to build the fuel lines and add some wire for the connectors and modify the throttle linkage. But it will be worth it in the end since it will run a lot better than carbs and it will provide a lot of tuning capability. If you aren't very good with computers you might want to find someone to help you tune the fuel injection.
I'd also use a Holley HyperSpark distributor so you can control the ignition curve with the Sniper. That would be a pretty good setup. You should be able to make about 800 hp and have it idle like a baby.