Should the barrel and ramrod holes need extra fitting when I install the barrel on the Woodsrunner kit?
No, the under lugs come already machined and slotted as part of the barrel, and the ramrod holes are already drilled, so the barrel should go directly into the stock without extra fitting once any chips are cleaned out. The one exception is if your climate is significantly different from the shop's climate, which can cause the wood to change dimensions slightly.