How to attach a new sill to an existing concrete foundation
The anchor bolts need to go well into the block, preferably at least 8" in. You should place the anchor bolts in the head joints of the 4" solid run.  No need to drill holes in the solid block. Worst case cut the solid block where you need to and set the bolt in the joint created in cut block. They should coincide in a hollow place in the rows of block below often enough to work in a bolt about every 4' maybe slightly more if need be depending on your seismic area. Masonry supply houses carry anchor bolts 16" or 24" long. In my opinion, you should use a minimum of 16", again, depending on your seismic area. There are other types of clips that will do the same as a anchor bolt.