see, thats the kicker... you're not gonna get the peace of mind of a waranty from any other setup..

I'm sceptical of the power ratings for the basic reason that its a 11.5:1 crvtec (stock bore) with streetable valvetrain. You can make plenty of power w/ this setup, but it usually plateaus around 240-250 whp, and thats getting into the realm of non-street-freindly cams. Aside from the block, its no different from countless other crvtec setups... and the block itself doesn't make any power, just ensures you wont break anything.

Anyway as for building your own:

BLOCK:
B18/B20 block, sleeved, bored to 85mm
stock crank balanced, knife edged
rods (IB,probe) arp rod bolts
11.5:1 pistons
gsr crank girdle

...that block would be just as good as the dart in terms of holding n/a power

B16 head
mild port/valve work
S2, Crower, Toda etc Cams and valvetrain (whatever you decide is right for a streetable allmotor setup)
arp head studs
cometic 85mm headgasket

That right there (admittedly simplified), with some good dyno time, would put you around 230-240whp... Parts wise, this would be much cheaper. If you're not willing to assemble it, labor would drive up the cost. If you can assemble it (aside from the sleeves, obviously) then you're saving a crap-load.

And of course, with a sleeved n/a motor, you could easily up the compression (probably up to 12:1 if you have decent gas in your area), higher if theres a local station w/ 95+

But then again, it all depends on whether youre willing to go through collecting all the parts and planning to save money, or if you just want to pay lump some and get a finished product...

If all youre willing to takcle is the vtec conversion/head mounting, a number of places (like camp1320.com for instance) sell custom built B18/B20 short blocks for ~3-4k.