If you plan on modding your motor, its worthwhile to replace the stock ECM. Currently you have an 8746. The prom in the 94 computer is not interchangeable with your ECM. The computer he gave you is actually a PCM, and not a direct swap, but it is a much better computer than your current stock one. Its also popular, so there is a decent ammount of support for it. If you want to use it, you will need to get the blue/red 32 pin connectors and repin your current wire harness to accept the PCM. Its not a real hard swap, takes about an hour to depin the ECM harness and place the pins in the appropriate positions in the new connectors for the PCM. You will also need a G1 adaptor and chip buring equipment as well.
The other option is to sell the PCM and get an upgraded ECM from dynamicefi.com. RBob will take your current computer and add an expansion board that gives you an improved OS and flashing capabilities so there is no need to burn chips. Both are good options if you plan on modding your car in the future or going to MPFI.
If you want to be cheap you could just get a chip or an ECM for a caprice that had a 350 with TBI, which uses the same ECM. You can also use a 7747 from a truck. The stock ECM is not very good from a performance standpoint, but if you just want to get the car running, than its a viable option. If you post in the classifieds here or on a truck board, people will be more than happy to trade you an 8746 or 7747 for the 8625 PCM
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