The car was build from following sources:

'80 323i chassis, suspension, Alpina wheels
'81 315 roof, doors, trunk, pedal box
'82 323i Recaro interior
'85 528e engine, tranny, harness, driveline, cat, ECU
'88 325i tranny, harness, ECU, head
'87 325i Block for new engine
'82 323i LSD, dogleg 5-speed

complete welded, repainted from green to polaris metallic
cut complete roof and replaced with factory sunroof (more details here)
front struts towers reinforced with E28 u-profile parts
new upholstered E21 recaros
rear headrests (modified and upholstered E23 headrests)
drivers side door handle from RHD model
rear pop out windows: shot1 shot2

all rubbers replaced
Bilstein HDs front and rear
lowered by TERRA springs front 60mm, rear 40mm - replaced by:
Alpina C1 suspension with AHLE springs and Bilstein sports
power steering
strut brace front and rear (with battery holder)
15" Alpina style wheels (OZ) with
Alpina replica lower front stress bar
BBS RS070 7J15 ET16 with 195/50 front and 205/50 rear
strut bearings with 5mm offset - see more

for detailed info click here

Swapped out 323i engine and auto tranny , replaced by 2.7l eta engine with 5speed tranny
2.7l i-engine (diesel crank, Schrick 272, i-pistons, eta conrods, Alpina B3 2.7 chip) 
adjustable cam gear
Alpina look alike valve cover
E28 driveline - cut to fit, center bearing was moved 10cm to the rear
325i E30 cat - now replaced with 525i M50 E34 cat
E30 oil cooler
3.64 LSD rear end
Remus exhaust on both sides with 102mm tail pipes
Sebring Header - Picture1, Picture2

more to see here

complete E21 harness has been replaced by E28 harness including:

E30 ECU 
E28 factory alarm (magnetic key)
E28 door locks (not jet implemented)
E28 instrument cluster in E21 dashboard (takes a lot of time!!) - till end of 2001
E21 style instrument cluster with E28 gauges and 260Km/h speedo (click here)
E21 switches on E28 harness (takes a lot of time!!)
E28 wiper control and motor
E28 fuel pump and transfer pump - now running with E30 intank pump
E21 headlight wipers
electrical speedo sensor installed outside of E21 diff
battery in the trunk
Blaupunkt stereo with disk changer, rear soundboard with 6"*9" 150W 4-way speaker, Blaupunkt 2*50W Amp
VDO gauges (Voltage, Oilpressure and temperature)
Clear turn signals rear

electrical door locks
5spd (dog leg) sport gearbox (still concerned about the short gearing)