The head most of these imported heads were cloned from is the Criterion DBL-202 boring head. This is a simple 2" boring head with three tool positions that allowed it to bore a hole from 0.050" to 6.667" ID. This head is found in almost every pro shop and a large proportion of hobby shops for a simple reason - it works, and it can work for decades if cared for. It has a direct reading leadscrew; what you dial in is what comes off the diameter, in 0.001" increments. The DBL-202 comes in two forms, the A-model that takes 3/8" shanked bars on the bottom and 1/2" bars in the horizontal tool holder and the more common B-model that takes 1/2" bars.
I have both A and B models and I much prefer to use the A-model because it uses the smaller, lighter bars. You have to remember that you are dealing with centripetal forces and mass makes a difference.
Cost for a brand new DBL-202B head ran about $300 so a used head in good condition should run about half that or less. The A-model is less common so commands a higher price.
Here is one that looks to be in decent shape, lacking only two of the three bar locking screws. The important thing to look for in a used head is that the dovetail gib is intact. It is connected to the body by a very thin remnant and can crack off if abused so look sharp when buying a used head. There should be three gib screws that touch the gib and all should be there; underneath each set screw is a ball bearing so look to see if the set screws are at the same level; if one or more is deeper then that means the ball is missing and must be replaced - I would pass on such a head.
I would take a good used Criterion head before buying a new import head but that's just me. I also have a Interstate clone of this head and its okay but you can tell the quality is lacking when compared to the real thing.
Insofar as boring bars go, you are going to find that inserted carbide bars will work for smaller diameters but the finish is going to be lacking in larger diameters. Carbide needs speed to work well and this especially applies to boring bars. Given that centripetal forces increase as speed goes up, going faster causes more vibration so that limits what a small mill can handle in terms of diameters. You will be far better off using HSS boring bars.
The best boring bars I have used are the cobalt-HSS bars from Borite. They cut well at mortal speeds, are sharpened easily, last for decades (my 3/8" set is over 25 years old and still looks and works like new) and finish far better than either brazed or inserted carbide at the speeds I use.
I think you can do well with an imported head but if it was me, I would prefer a used/new Criterion head. I would go for cobalt bars instead of carbide. LMS sells a cobalt set that looks good.
