No experience personally, on using one in a rebarrel job.
I do have one (SW 1500 , made by Howa), and it is one of the best made, best designed rifle actions on the market.
http://www.legacysports.com/products/howa/howa_baractions.htmlCompare Howa with other factory barreled actions:
• Forged steel, flat-bottomed receiver with large recoil lug and hammer-forged barrel.
• Heavy Varmint barrels have recessed muzzle crowns.
• Forged, one-piece, bind-proof bolt with dual locking lugs, M-16-style extractor and large cocking indicator.
• Three-position safety allows safe single-loading and secure bolt lock-down.
• Bolt and receiver are ported to vent away high-pressure gases in the unlikely event of a pierced primer or ruptured case.
• Receiver rings are precision drilled and tapped for accurate, rigid scope mounting.
• One-piece guard and magazine box with hinged floorplate.
• Choice of short and long actions, standard and heavy barrels, in blued and stainless steel.
Weatherby uses the Howa action in the Vanguard model. The claims about inaccuracy are wrong. Howa/Vanguard had an accuracy guarantee of 3 shots in 1.5 moa at 100 yards for years (marketing angle). Their quality is top notch (forged action, one piece forged bolt handle and bolt body for strength.
As for aftermarket options, there are certainly all you need. Howa's take the same scope bases as Remington 700's (did anyone know that?). Stocks are available. Triggers are available (Timney). What else do you need?
I've read that there is one glitch in rebarreling a Howa. As I understand it, the barrels are difficult to remove from the action. To remove, you must use a lathe to make a small relief groove just in front of the action-then it is easy to remove. I think I read about this on accurate reloading.com in the gunsmithing section. I have read it multiple places, so it should be relatively easy to find.
In short, go ahead and do the project if you want. I think the Howa/Vanguard action is top notch, high quality, well designed, well made. They've been around for 30 years and are not going away.
Good luck with your rebuild / rebarrel project.