Are you currently use the Race head or Econo Head?..
There are some new Econo heads for sale over at Moparts.com on page 7 of the Race parts for sale..
As far as your question about drilling for oil...do not know ...but I guess anything is possible, but one thing you might want to check before investing any money is whether the rocker stand mounts are the same as your existing race heads...
I remember Mopar ran off some more Classic W2 heads a few years ago..but they are no longer listed in the catalog...there got to be a some new sets floating around somewhere....