Those RPM ratings are rarely correct. You have to build around the heads, not the other way around. I’ll take the better head any day over a smaller head. As long as the bigger head isn’t bigger because someone just ground the hell out of it.
A correctly shaped, larger port is almost always a better deal when you account for it. That means not using cheap headers (there’s a reason why the fast guys spend 2000-3000 bucks for headers), that means not using an off the shelf cam, and spending a bit of time on the phone with the cam grinder, not texts or emails. You can’t duplicate the flow of a conversation in texts and emails like you can on the phone.
I’d also consider a 50 degree seat on those heads. The steeper seats help with low speed air flow and reversion, but again, the cam grinder needs to understand that, and I’ve talked to some who say it doesn’t matter. But it does.
The bigger head will most likely take less port work to get it in shape, and you can take your money and time getting the intake manifold in shape.
Compression ratio makes a big difference when using a head most think is too big for the application. IMO, the closer you get to 12:1 the better off you are, and if you do it correctly, you can still use pump gas.
If you can’t spend close to 1k on a converter, you’re kinda wasting your time no matter what you do. I just ordered a PTC drag week style converter for a street/strip deal for a friend. 8 inch housing and an 8 inch stator. Should get him to 5000ish for flash stall, and with his transmission cooler he can drive it anywhere. Well worth the 875 bucks for a custom converter.
IMO you can use those heads. It’s attention to detail that makes or breaks a build. I’d use a single plane intake with those heads, and a carb with nothing bigger than a 1.470ish venturi. Anything bigger and it starts to kill the bottom. Buy a carb that has changeable brass, like a QF Brawler (just cleaned one up for a friend so they are pretty tuneable but out of the box they have some stuff I don’t like) or the ProForm carbs. The PF carbs are a pretty good bang for the buck, but again, you need to go in and clean up a few things, and then tune from there,
Of course, this blows up and buries your budget. That always happens. Speed costs money. Spent wisely, you can have an overachiever. Spent like a drunken sailor (no offense to sailors and marines) you’ll have an underachiever.
Just my .02 cents, and it’s worth EXACTY what you paid for it.