I've had 2 Ford 460's, one in a C, the first Coachmen Leprechaun with one after the high heat Dodge, and one in '90 Oshkosh chassis 37' GS Friendship.
If you check the torque, you'll see the 460 provides more. I jumped on the E460 C as I was living in Holbrook AZ and it really made significant difference driving in the west with mountains, high winds and high altitudes. I totaled 108k on those two in seven years with no problems.
The class A was a coach too large for the wheelbase with about a 12' hangover by stretching the frame. It also weighted far more than the C and really was Bev and my first home until we bought this house in 2000.
The A's engine ran very hot, had all the manifold problems mentioned. the plastic breather opening was way to small and the pipes were the standard small tail pipes and muffler. My first trip was back to Albuquerque to have all that fixed by Jim Statkus. WOW!!! Headers with those big pipes and largest muffler Midas made would have given me even more oomph in lower gears.
To make use of that torque was a problem here in NM at altitude as the Ford 3 speed trans would lose rpm between 1 & 2 esp. Try starting at over 10k' and climbing uphill. So, I went with a Gear Venders Gear Splitter. That fixed that issue and gave a true overdrive as well.
I'm looking at an '86 Ford E350 with the Ford 460 chassis with the '87 26.5', rear bed, overhead queen, front lounge & sofa Tioga fiberglass shell body. Do dings, no inside stains. It is on a lot here in Bel?n. It haven't crawled under it yet but it has the 3.5" tail pipe, roof and auto air works as does the Onan Emerald I. The newer Dometic is a RM-2801.
He's asking 7.5k but isn't worth more than 4+ as the rear tires are 6 yrs old. I haven't had the engine checked, but will.
Its a way to get back on the road.