You made a good choice by going with the 20v, and you will be very happy with the swap. I would ditch the factory ECU and AFM, and definately go with Megasquirt n' spark.

The new generic trigger wheel code is awsome. It allows MS to use the factory distributor inputs and fire the original ignitor and coil. We just finished a paseo running a turbo 20v with a GZE 8.0:1 bottom end. The engine made 218 whp at 1.0 bar. MS is really close to being a inexpensive drop-in replacement for stock computers.

They also have written code for the mixing of Map and TPS inputs. I found this to dramatically smooth the off idle to partial throttle transitions for the 20v, which allows the driveablity to amost parallel the factory ecu.