going only by the sonic test reports alone is not the best way to approach a solution IMO. it's just the beginning step. we routinely sonic test blocks but we also follow up by fixturing the block in our CNC machining center to find out if the bores are in the correct location to start with. i can tell you on many of the R blocks and X blocks we've tested, they very often aren't. sometimes that works for you, and other times against you.
you do have the ability to move bores in the front to rear plane up to a point, but i don't suggest moving them away from the true 45 degree angle from the crankshaft/camshaft centerlines. quite often that crank/cam 45 degree angle is already out of spec as well.
if you have a shop with a CNC block machining center that can check all of the important measurements it would be a good decision to use them IMO. i probably have some pics i could post of different R blocks we've done where the bores were actually at 47 degrees as cast. some of the bores were considerably out of blueprint spec in the front/rear plane as well. when we corrected the geometry it actually helped the sonic numbers. like i said, you just never know unless you have the abilty to follow up with the newer type of equipment available today.