I've got a 1955 Oldsmobile 98 Holiday with the Rocket 288. Was thinking of putting in a newer Chevy 327 or Oldsmobile 350. Anybody heard of an engine swap or upgrade for these old 98's?

 

You should have a 324 Olds in there if it wasnt changed by someone else. Years back a friend put in a 305 Chevy in a '55 88 and it was such a pain in the neck because the exhaust manifold on the drivers side dumped directly on the steering box. Why would you put a dime - a - dozen Chevy in there? Be original ! At least go with a 394 which can physically bolt in there

 

PLEASE don't throw a belly button engine in there! I have a '54, with 324 engine. I have pulled this engine, and it sits in the corner of my shop, awaiting a full resto, In the meanwhile I will use a 455 Olds engine.
You have a classic car, don't use a common old chev engine, My opinion, is it'll loose a lot of character.
It's your car, and your choice, but you asked for opinions.(?)
Good luck either way, & let us know what you decide to do.

 

An upgrade would be an Olds Big Block! Actually I agree with fishydoo, find yourself a nice 324, 330 or 394. Nice period engines for your '55. An Olds 350 would probably fit without too much trouble as a temorary powerplant, do you have the tranny to fit it? because I am not sure how easy it would be to fit the original tranny to the new engine.