those Olds deltas were one of the best selling cars of the year in that time frame. they are nice driving cars.
bolting in a gas 350 can be done in a weekend.
it's a easy swap. i know several people who have done it. i have head all the gas wiring is still in the engine harness. just unwrap and everything plugs in.

back in the days i used to own a 80 caddy Eldorado diesel. had replacement motor with a new injector pump installed before i bought it. i probably put 50K miles on it in under 2 years.
was a fantastic freeway driving car. got 25+ mpg while driving 75+ on the freeway. i .loved that car when i was driving all over the us from car auction to car auction. i was a used car buyer for a multi location car dealership. i had to buy at about 50 cars a month. i was on the road about 20 days a month buying cars.