There were 3 designs of bumper in europe
the 1300 with quarter bumpers and overriders
the 1500 with extruded alloy "girders"
there was also a limited run of single piece plastic bumper (copied for the eurosport type 1 design) for the 1500
The 1300 had a full chin spoiler as part of the bodywork, all the later cars had the spin spoiler as part of the bumper assembly so if you want to convert a 1500 to the 1300 design you will need to find the extra panel from somewhere.
To make things more complicated there were a number of different designs for the federal spec cars but I don't think they will be of any interest to you.