It has been done, and I have searched about it. It seems the only thing that needs to be done is, in order to use the typical style of aftermarket turbo manifold, one part of the housing needs to be clocked so that the oil drain will work right. Other then that, is there any other considerations? I don't know much about the 14B turbine, except that it doesn't cost much.

Is it internally or externally wastegated? What flanges work and which ones don't? What else do I need to know to use a 14B with a 420A?

It's internally gated. You'll either have to use an external wastegate, or modify the internal gate to produce less boost. It will need a Mitsu flanged exhaust manifold and turbine flange.

I used a 16G, had to rotate the comp. housing and the exhaust housing relative to the center housing...

Quite a pain in the ass to get it right and to make a downpipe...
Also, you have to put a lot of work into getting the wastegate actuator to work right...

Take a look at my pics of my 16g on my ebay auction and you can see how I have things rotated, and on the one turbo pic you can see how I had to machine a wastegate actuator mount for the right anlge...

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=2474347457

Lee.