Bluebird/Avenir/GTiR motors will drop in to a B13 or B14 as long as you use the original fwd tranny (usually manual).

Motor to motor, there are few differences. The demand is really what makes the rwd motor more valuable. Look at the local tampa demographic... There might be 30+ rwd sr20dets around, but I'd say less than 10 fwd sr20dets. The ratio may even be more skewed.

Chris