Hi Hunterdude,
Are you set on a kit? The reason I ask is none of the English fowler kits of which I am aware offer anything other than export or trade versions of English fowler. Based on some indications by Jim Kibler last year, his fowler may also be modeled on a trade or export grade gun. I don't believe any have hooked breeches, keyed barrels, or really light weight barrels. In my opinion, none available today offer the light weight and balance of real 18th century English fowlers. If you look at our tutorial section under "Miscellaneous Tutorials" is a multipart thread showing how to build a light and lively mid-18th century English fowler. In additionis another multipart tutorial "Understanding the British Fowler". In my opinion, the best barrel commonly available for a light and lively bird gun is the 42", 16 gauge Griffin profile barrel by Colerain. As James Rogers mentioned, Rice makes a light barrel from 4140 steel but the version I saw at Dixons has a trade gun like profile not one commonly seen on higher end guns. The Griffin barrel has a rapid taper from the breech closer to true Spanish barrels than any other offering. For me, the current "Holy Grail" of fowler barrels is a Colerain Griffin barrel, 42" long, 16 gauge and "D" weight such that the breech is almost 1.25" in diameter. With that barrel, the balance point can be made to be just in front of the lock. Light and lively for upland birds.
dave