Depending on the power level you are building for is the best criteria for bushing lifter bores.For street and strip the cost could be well spent elseware.on mild builds it should be done only if correction is necessary ie:loose bores,location and misalignment to the deck and heads.On all out race engines it is done for the same reasons and for custom lifter location to better the pushrod and rocker alignment.
If you choose to go this route be sure your machinist has the correct fixture or program for your block and application.Be prepared to pay $400 to $600 plus the cost of bushings.Also make sure that the block has all been corrected(squared and etc).The lifter bushing should be the last machine work.Ask first if your shop has the means,equipment and ability to do this process,we have seen bushed blocks that are totally screwed up because a shop had just bored and installed bushing.We agree that factory machine work is suspect at best,and should be checked and corrected if necessary.