In circle track racing with a sb it's standard practice to bush the lifter bores. It's done for oil control, if a pushrods were to break and a lifter leave the bore then the engine won,t loose all oil pressure and grenade a 7000 or more rpms . It looks like that block has been welded. I would say the repair is only as good as the quality of the weld and the acuratcy of the machine work for the bushings.
Me.... I'm a little anal and don't trust other people's work generaly and like to do it myself so I know it's done right. Or at the very least thouroughly measure eveything.
Just my two cents....