A lot is dependent on the build itself and the target of the build. In the quote you quoted, the statement was made from a certain perspective. Without going back and trying to figure out what perspective I was making my statement from, I’ll say that the cylinder head on top should fit the builds target.
For the most part, I have found it a plus to put what some people think as t much head on top BUT a well ported head is worth a lot of power even when it seems silly to use that much cylinder head.
There is a point of which the port becomes too big for use. Where this is, is a variable point. It’s also not just the engine but the car and the drive train behind the engine. Not enough stall, gear, to much tire, a heavy car, over cammed, too big of a carb, etc….
I don’t know what the 340 heads you’re looking at are cost wise, but, IMHO, I think probably you would be better off looking at and getting an Edelbrock cylinder head. As cast, they flow about as well as a nicely prepped and mildly ported 340/360 head.
The 318 heads ported are a lot of work and it’s something I personally would not invest time into. Ported 318 heads, done really well, will flow about what a good stock X casting will with some prep. If your 318 heads are professional ported to it’s best, they will equal a nicely worked on set of 340 heads. In other words, there always a step behind.
If you’re intent on building a 318, start a thread on it where it can be discussed at length.
I’ve done a 2.02 on a 318. It’s fine.
I would not do this the way I did it 30+ years ago! J heads with a 2.02/1.60. I’d do the Edelbrock head. It would go pretty far on a 318.