chris, if the heads still have 3/8th valve stems(which they should if your runn cast), you can buy comp lash caps and they should fit your retainer locks. i'm runnin lash caps and i really like how they spread the load across the valve assembly instead of just the valve stem tips.
if you do go without, look at your pushrod length again, without the lash caps, the rocker roller's postion ontop of the valve will change, sometimes for the worse