Ive done a lot of research in the last few days...

B20z longblock, including manifolds(not that you'll want to use them), TB, distributor is $749 from hmotorsonline.com

A GS-R intake manifold wont work, but an LS one will (could get that extrude honed in denver)

any B-series exhaust manifold will work

LS ecu is plug and play

The B20z is MUCH preferable over the B20B because it actually has somewhat of a top end (20 more hp than the B), and is improved slightly throughout the powerband by the 9.6:1 cr. It doesn't look like the intake manifold (with big resonator chamber) will fit under the hood of a civic, but I'd try it out. If not, an LS manifold is a direct replacement and cheap as hell. Plus, the stock b20 exh. manifold is a cheap stamped steel POS, so that'd have to go

So the rundown:
B20Z longblock $750
LS ecu $120ish used
LS intake mani $40ish used
Si/gs-R exhaust mani $100ish used
gs-R/Si tranny, axles, shift linkage $800ish used

so figure in shipping, and thats about $2100-$2200

use aftermarket header instead of used exh. mani, thats a couple hundred more, get your LS intake manifold extrude honed, an extra $75.

It seems as though for about $2500, you could be making 138hp and 132lb-ft to the wheels. Sounds like a deal to me.