Iirc 88 has the alternator on the drivers side. There are length differences between birds and Camaros since the battery and ccp are on the passengers side.
You might consider doing the 870 to 165 repin and addition of relays.

 

It's going to get more complicated the further you go from the same year and options, like 88 would use a different wiper motor, things you dont normally think about... To do it right, you'll either be splicing parts of your old harness into a later harness, or changing parts to match the later harness's donor car.

 

http://f-body383.tripod.com/AAB/870-...pRepinning.htm
Information on the ecm swap

 

'85-'86-'87 were two piece harness, gauges, starter, sensors etc.
the other one was for the tuneport
'88 was one piece, everything in one harness.

None of those interchange, but like Drew said, you can splice things together.

 

 

You might want to double check c100 for differences before you plug it in.
http://www.austinthirdgen.org/?pid=19