Whoever builds your gun should use a VangComp barrel, period. I have a GunSite Rem 1187 with a VangComp barrel and it is simply awesome!!! I cannot say enough good things about that barrel. #4 Buck is as small as you want to go (really #2Buck is the best lower limit) as anything smaller really opens up way too fast. Triple Aught to #1Buck in this thing is the ultimate for those hard to solve close range urban situations
Having spent some time researching this subject myself, I feel both of your choices are good ones. There are a lot of good gunsmiths out there who can rework a "social" shotgun but, at this point in time, my money on an 870 would be spent with Hans Vang. He's not the cheapest on the block but, not the most expensive either and you get a lot of value for the dollars spent.
Sid
---
Tx FFL
[This message has been edited by Sid Post (edited August 03, 1999).]