There was never much info ( or speed equipment ) for tweaking the straight 8's. They were considered overweight, a "luxury car" motor and not often used in Hot Rodding. But some Inliners like that kind of challenge (see picture below)!
You should probably swap up to a 320" motor from a Century or Roadmaster model, as a first step. Fisher Books has a 1954 California Bill book titled "Chevy GMC & Buick Speed Manual" that has some Buick info, but it's mostly basic Hot Rod stuff like raising compression, regrind cam, more carburetion, etc. It's available at Amazon.com.