agu 20v ecu re flashing and loom conversion

Hi, very new to forums and would like to thank all the people that put the time into these sites, am still understanding post topics sickys etc..any how I am sure this has been covered before but, I have decided to 20v my Mk1 golf cabby gti it had the dx engine and k jet system, am using the agu mk4 engine and want to run the standard ecu which i believe can be re flashed to remove immobilizer, and any other system like abs that are not used on mk1 and thorugh i had read on here that there  was some doing this any help please. :?