Nice car. Good luck with it, Power and performance options are endless. It probably more of a budget thing unless you have a specific preference. Even if it is a olds motor a small block chevy should bolt in there pretty easily. Ls is badd *ss but alot more work and money so Its all upto you. If its a 305 youd be surprised what a set of headers, intake carb and maybe even a mild cam would do. I had a 305 once in a Malibu, it came ot of 76
caprice classic. That car was ridiculously quick. Nobody ever believed me when I told them it was a 305. I had headers, edelbrock cam intake and a gone over rochester, msd 350 trans with a shift kit and 342 out back. I used to run with 5.0 mustangs all day and this was when they were pretty new. I have a 350 now with a similar set up and it doesnt even come close to that 305 I had. Maybe because it came out of
caprice, it mightve had higher comp or good heads, I dont really know. Wish I still had it.