really all depends on your coin-box and its depth.
The easiest , cheapest way to go would be another small block , that way your bell housing would still work out with the engine.
Got cabbage to spare? Big block. 6 speed Vette trans. Tub it out.Ford 9" rear.4 wheel discs.
Better bet would be to go over the brake system front to back.Check/replace bearings, bushings , etc.Get a fire extinguisher.Make sure she's safe and sound and then have some fun.
Or just drop a hemi in it! Dare to be different! Max Wedge in a chebbie?! oh ,the blasphemy!