The studs will pull the threads in the block all the way to the bottom of the studs, not the top three or four threads like the bolts do Bottom line is if there is any doubts in your mind on the need to do it, do it and don't look back If you can take it, the block, to a good machine shop that has a decent dial bore gauge try torquing the main bolts down with no bearings in them and measure the bores for size and out of round, do all of them and write the results down and then remove the bolts and put the studs in and remeasure the bores. If there is more than .0002 differences go ahead and have it line honed, way better to be safe than sorry