In your situation, I'd save and smoke your dad's pipe as it is and hope to buy an estate 904, or perhaps
eventually a new one, to be outfitted with a churchwarden stem. Since the stem is designed for an only
marginally bent stem, I'd go with a straight churchwarden stem or one only slightly bent. But I'd keep
your dad's pipe as is, since it has powerful significance for you. Once you have the churchwarden 904,
keep both stems. You may find you would get more use out of the shorter stemmed pipe. Alternately,
you might like the Savenelli 601 churchwarden (non-filter pipe) that appears in my avatar, an excellent
smoking pipe reasonably priced (less by $30+) than a new 904 (Oscar Lucite series). Your dad's 904 is
one of Sav's most distinctive and artful shapes, in my opinion.