Yep, all barrels with fit the early frames. Only frames and barrels that won't are the Armour Alloy II's unless they've been reworked (basically they take the AA finish off the frame and lug so they accept a standard pivot pin.)
$350 is okay, not great at the moment but prices go up and down. Without the easy opening conversion ($55 plus shipping last time I looked at Fox Ridge) I'd probably only go $300-$325 if it was in very good condition. If you check Eds, gunbroker or auction arms, you can see what 44 mag barrels are going for. Eds or James Lewis usually have frames for $175-$200, just have to add the wood and barrel to compare to your $350.
Helicopter Bill