My Dad picked up a new toy

Might consider a 2.2L Turbo. If you find a parts car, get complete engine w/accessories, radiator, fuel tank with pump, wiring harness, logic and power modules,and transmission linkages. I did a conversion on an Omni and it was all bolt-in. The turbo will give about 50% more horsepower, but it feels like double due to the increased torque over a large rpm range.

Yep, I tried. I have had several L-bodies in the past. 83 Shelby Charger came with a Holley 4bbl on the 2.2, 84 Daytona Turbo, 86 Laser, 88 Daytona Turbo Z. All fun cheap cars.

He wants to keep it close to original as he can. He is an old fart at 61. His hotrod is a 74 Duster with a 413 built for twin turbos in the future.