The majority of the engine harness will be similar, but the routing will need to be reworked and some of the wires may need to be extended. These diagrams are for a Chevrolet, but they should be similar to the Olds.
I assume you are starting with a Buick V6 - distributor in the front. Not much will exchange. Need the V8 fan shroud and motor mounts as well. The transmission will need an adapter plate or buy the whole drivetrain complete with belts and pulleys. Consider a 700-R4 with a computerless lockup kit - buys you better acceleration without changing the highway gears in the axle. Lots of other suggestions but I'll defer to your original question.
I take it you already have the 305? Other wise we can’t understand why you not going bigger/better. Granted the 305 is better than what is in the car. A good majority on here have pulled the 301s,305s,and 307s for the more powerful bigger engines. Not criticizing ATALL, it’s your ride do what pleases you.
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