I've always loved Oldsmobiles, at least the older RWD ones. I owned this '84 Cutlass a couple years ago:
Had a mild 350, TH350 with a shift kit, 3.23 limited-slip rear end. Glorious sounding long-tube headers and dual 2.5" exhaust. Bought it cheap with the intent to fix some minor mechanical issues then sell it again. Wound up driving it for several months before parting with it and I wish I'd never sold it.
More recently I drove this boat around for a month:
Bone-stock '73 Olds 88. 455, TH400, probably 2.73 rear end. Exterior is a little rough but the interior is near perfect. Just floated down the road. One of my coworkers lent it to me for a few weeks while I was between cars. I'm still trying to convince him to sell me the thing. It's really nothing special, but it gets a lot of attention.
That guy is a bit of an Olds nut. He's also got an early '80s Caprice with a 450hp 455, built to handle as well as a land yacht can. That build was practice for his next project, an '80s Cutlass with a 700hp Olds 455. He's currently got the chassis and short-block for that car together. Probably be years before he's done with it though.
Probably not that drastic of a change. Maybe more like 300hp. Consider that they did drag 4,500lb FWD Toronado's to 60mph in around 7 seconds. A bit faster than a late-model 250hp CVPI that weighs 500lbs less.