We have Cosworth 2.5L short blocks on the shelf :
# Cosworth EJ25 short block includes the following:
# New Subaru EJ25 STI Engine case
# New Subaru EJ25 STI Forged Crankshaft
# Cosworth Forged H-beam Connecting Rods
# Cosworth Forged Pistons and rings
# Cosworth Coated, Tri-metal bearings
# Balanced to within .5 gram
# Complete blue-print assembly
# Ring gap checked
# Bearing clearance checked
# Deck height checked
# Connecting Rod side clearance checked
# Crankshaft end float checked
The short block is assembled by Cosworth in house. You will need the following bits to complete the long block:
Heads
Headgaskets
Oil Pump
Timing Belt kit
Water Pump
See here :
http://www.cosworth.com/Default.aspx?id=1091700
If you want a price, PM me and I can quote you both on fitting + running in the engine or to just supply.