I have stitched many blocks/housings over the years with just brass screws/bolts. The Lock-a-Stitch works great too. It is faster than using brass screws. It would depend on the length of the crack weather I would go with the cost of the Lock-n-stitch kit.
Blocks and housings repaired with this stitch method are fine to use. If done correctly you can't hardly tell where they are used.
I would NOT WELD a cracked block. Unless you do it right it is just a band aid repair. To do it right you need to preheat the block to almost cherry red to get a good full width/depth weld. After that the block should really be re-machined. For a tractor that is not really rare I would just replace the complete block before I welded it.
Here is a video of the Lock-n-stitch kit being used. You can do the same thing with brass screws. The reason I always used brass is that it expanses faster than steel/cast iron. So the stitched seam has less chance of leaking when hot.