You have half the battle because you know the house side. The 454 is a real gas hog. I had one in my 87 Allegro and now I have a 8.1 Vortec on a smaller Class C at 26' and it does much better. The V10 is a good motor, based on what I have read on the forum. In looking at early 2000 MH, when we were shopping, I didn't find many with the 454. I would try and stay with the V10. If you know trucks then you will be able to know what right or wrong with a MH. Not much different, but bigger.
I know Redmond is a ways from Chehalis, but try looking at Ulhmanns in Chehalis. We bought our 03 Chateau there in January and are great people. I also liked what I saw and heard from the people at Sunset RV.
Good Luck
Arnold