You have a classic bike, also with sentimental value. You may wish to clean it up, make it rideable again, and use most of the original parts.
Original, in this case meaning original to your Dad's bike, which he received second hand, and made some changes to by himself, over the years.
Or maybe it may receive some upgrades?
Things to consider, some Westfield bikes may sport some odd dimensions (in the areas of headsets and bottom brackets; cups and cones).
Looks to be getting 90-years old soon, wonder how many colors of paint it received over the years, and if any original brownish-red paint might be left underneath.