Having both a rather pepped up N/A B20 in my PV (175 hp?) and a somewhat pepped up B230FT (250 RWHP, based on 1/4 mile times) in my 245 it's my opinion that:

- Adding HP to a normally aspirated motor very quickly climbs a sliding scale of increasing cost/complexity and diminishing returns. It's easy to make some initial simple gains, because the Volvo motors were (probably intentionally, in the interest of longevity) somewhat corked up from the factory. But the whole process rather quickly devolves into a game of microscopic gains at expansive cost. And the ceiling (what you can reasonably expect to acheive) is pretty low too, probably 180hp for an 'advanced shade tree mechanic', 200 - 225 or so for a more professional engine builder who can really maximize all the small things. Which isn't to minimize that accomplishment at all, a stout n/a motor is very fun, but...

- Adding HP to a turbo motor is dead simple. Starting off with a junkyard B230FT any yahoo can get up to 200, 250 hp with just a $25 MBC and maybe some $40 worth of junkyard ford browntops. There is (as with anything) still a curve of increasing cost/diminishing returns but in the world of turbos, it's much flatter. Spend the same effort as you would in making a 200 HP n/a, and you could probably have a 350 hp turbo. And you'll have used far fewer esoteric parts in doing so, as well, mostly fairly common junkyard parts (turbos from later cars, truck intercoolers, etc). And turn the boost down on a 350 HP turbo motor and it's still a friendly daily driver, too.

Cliff's notes: Swap in a B230FT. Megasquirt it. That's my $0.02.
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'63 PV544 rat rod, '93 Classic #1141 245 +t