There's nothing wrong with 289 blocks. The earliest blocks made before 65 had the old 5-bolt bellhousing, but any after that are 100% interchangale with 2-piece rear seal 302 blocks. 289 blocks can even be used in place of late model 5.0 blocks as long as a 2-piece rear seal crank is used. Pre-85 blocks just aren't set of for hydraulic roller cams.
Speaking of 5.0 roller blocks... these are weaker than the 289 and early 302 units. They had a lot of meat taken out of them to save money on production and to make them lighter. The 50oz-in 5.0 cranks are more flimsy than the early model cranks as well.
289 and early 302 blocks are functionally identical, and are completely interchangable. Yes, they have the same 5 1/8" long cylinder walls, and are both fine for stroker kits.
Good Luck!