B230 bottom end is significantly better than a B230 for NA power. This is due to the smaller (lighter, lower friction) bearing journals, and the longer conrods.
Where a turbo motor can benefit from the B23’s extra beefiness, it is all negative for a NA build.
Here’s what I would do:
B230F block. Conventional/turbo wisdom is that you want the later one with the slightly beefier rods and much better thrust bearing design. I suspect that this is irrelevant for a NA build.
Either way, I would fit aftermarket longer rods and shorter pistons. This will also allow you to get in the ballpark for compression ratio without having to machine the head too much.
The 531 head is the best head, but it is massively over-rated compared to the much more readily available, and much cheaper 405 head.
Whatever head you choose, pay attention to getting the squish band right, and you will be able to increase compression ratio without more hassles with detonation.
The readily available extractors and pretty much garbage - any performance gain you might get is from weight loss alone. Either buy/make some proper design extractors, or use the factory manifold. There are some ok ones available secondhand, but they are few and far between.
A better ignition will help. Ideally a fully programmable one, but I THINK a 123 Ignitions dizzy would be an improvement over the factory Volvo setup.
