This information is complied from old VWVortex posts, internet searches, and my experience as we build a MK1 with an ABA swap.
We are swapping out what was left of the original a MK1 Rabbit GTI engine and replacing it an OBDI ABA motor from a 1994 golf. The car is being converted completely to CE2 for both the plug and play aspect and the original MK1 wiring being in poor condition.
Engine / Transmission Mounts
The ABA is essentially a direct drop in to the existing engine/transmission mount positions. Use the MK1 mounts from your old engine and transmission (I am currently using the original GTI transmission) and install them on the ABA.
The ABA timing belt cover will need to be trimmed or removed to accommodate the MK1 mounts.
The hood will not hit the engine unless your setup is an OBDII. If this is the case, you will need to flip the throttle body to ensure there is enough clearance.
Throttle Cable
I used an 16v cable purchased from MK1 engineering. Worked great and came with a new pedal and firewall grommets. I have included the link below.
Serpentine Setup
I am currently not running AC or power steering. Therefore the serpentine set-up will be just 3 pulleys.
ABA Tensioner
ABA Alternator
ABA Water Pump with VR6 Pulley
Belt
I used was a 6 rib, 40.5" (1033mm) serpentine belt. I am sure it can be found at most auto parts stores. I ordered mine on Amazon. I have included the link below.