H Series motors are not common now, you hardly find one now a days, so is the B series, apart from its rarity its expensive too, so is the case with K Series. But still if you want to spend money on a Fwd project, I would suggest to go for a K swap. Easily available, parts available and tons of aftermarket support.
But again, if you can spend a fortune, a Merz with a 2JZ anyday over a Fwd project car.