If you can find a Luxor in good shape, I'd jump on it. I think the Luxor had an 8.3 big block, which would make it a very capable rig. It's a step above my Vectra, and I love my old rig. My 5.9, 6 spd, 230 HP, 600 lb./ft pulls a 3,000 lb. Tacoma just fine since the 35' MH only weighs about 22k loaded (no slides). We averaged just under 10 mpg on a 4500 mile trip last summer towing, without having one single problem.
To have the expectation that any of these rigs will climb a hill (with or without a toad) like a car is to end up very disappointed. My little 5.9 will run down the road as fast as you want to go, no problem. I try to keep it at about 62 mph (1900 rpm), but if I start overriding the cruise, will find myself running 75 before I know it. I suggest focusing on the condition of the unit, and avoiding anything that doesn't show pride of ownership. Any of these older diesel rigs are very competent motorhomes.
Thanks for keeping us informed. It's exciting to see someone selecting their first motorhome when they have done their homework like you have!
Ken & Jeannie
96 Vectra Grand Tour 35' DP
Jacey (terri-poo, waiting at the rainbow bridge), Jack (silky terrier)