The block is cast, cured and machined as one piece, correct?
You will need to learn on how much preload to use on your hone by hands on testing the preload to make sure it is removing material and not polishing it If it is not slowing the drill motor down under the load compared to unloaded it is probably polishing it instead of removing material
Another thing to check before you continue is the cam to make sure it is NOT bent
Been there, done that Cast iron cores and steel billet cams can get bent, both can be straighten also by a good shop
Don't we love trouble shooting