Hydroboost followup questions

[earl84]

I have successfully installed a HB out of a 2004 Chevrolet 3/4 ton truck in my '66 C20. The brakes work great, but I am having a few issues and have some questions.
The first and biggest issue is that the brake pedal is slow to return to the rest position, and I wonder if this slowness is causing what is really my larger issue, which is intermittent brake drag. Doesn't happen all the time, but it does happen. When I did the install, I put in a 90 degree fitting on the return side that I drilled out the orifice to be the same size as the stock straight fitting. Flow may be restricted there, but companies like Hydratech sell the same fitting, and apparently don't have issues. I run my return lines from the HB and the PS gearbox to a T fitting, and they are plumbed correctly, but there may be some restriction there as well.
Has anyone else experienced this? Could my HB unit require a rebuild? I can't remember the name of an internal part that I have read that may be a cause for the slow pedal return.
My second issue is that the steering is overly sensitive. It's freakin' awesome at slow speeds, but at highway speed I really have to be on my game, it is ultrasensitive. I think this valve http://www.summitracing.com/parts/hdt-ps-101 might help in this area, does anyone have experience with this?
Also, does anyone know if the brake line ports on the 2004 master cylinder are the same 1/2-20 (3/16 line) for the front brakes and 9/16-18 (1/4 line) for the rears? I would like to use the 2004 master to see if that has anything to do with brakes not releasing fully. Currently have a '79 C20 master cylinder mounted.
Oh, I also replaced the combination valve, thinking that may have had something to do with the brake drag, but it had no effect.