Went ahead and purchased a rebuild A1-Cardone Hydroboost power brake booster part number 52-9383
from Amazon.com for $171.39 (163.39 +TAX) delivered. Looks like it fits all P30 motorhome chassis models from 1982 to 1994.
All the symptoms seem to point in that direction and I've already done the following with no great improvement:
New Dexter TAG axle brakes with new Prodigy P2 brake controller (old controller was water logged and I got a great deal on this one)
New front rotors (Old rotors were badly pitted and rusted)
New front calipers (Rock auto had a great deal @ $14 each rebuilt, loaded and delivered from Wagner)
New Wagner thermal quiet brake pads on all four axles
New brake flex hoses (Old ones had collapsed)
Previous owner replaced the master cylinder
Flush brake fluid with DOT4 synthetic
The fact that I feel a strange push back pressure at the peddle with no apparent power braking and no power steering issues indicates to me that it must be something related to the hydroboost unit its self and not the power steering system. I may go ahead and replace the return line as well since it's there, easy and cheap.
Not looking forward to doing the swap, so any input would be greatly appreciated. I think the biggest problem I'm going to run into is getting the power steering hydraulic feed and steering gear lines off the hydroboost unit. My suspicion is that this is the original 1992 hydroboost unit since it still has the blue accumulator attached.