I went with the ford 460, a few reasons. One I had a 95' Chevy K3500 4x4
diesel truck, in 27K miles Three major engine repairs, broken front seat,
not the motor but the "D-Frame metal" also a broken, turn signal/hi/low
beam. All was covered under warranty but, three major engine repairs!
The Ford Chassis is heavier, but It dosen't flex like the Chevy.
I bought a low mileage 97' for $24,900 before gas went into the $3.00 range.
Only repair/replacement was a coach battery (about $50).
The RV dealers recommended premium gas with the 460.
I have used a mixture of 87-93 octane with decent results in the hills of E.
PA and NE PA.
I put on about 1600 miles since purchase. I get about 7-8 MPG.

My motorhome started making some noise when accelerating after 1000 miles, I
asked a reputable mechanic who stated that it is belt noise (no charge) and
not to worry. He looked at the belts and showed me how it the tensioner was
loose it would squeal more.
There is a known fan clutch problem on the Chevy's.
My thoughts only, YMMV.

BTW: this was also my first MH, I had a pop-up prior to this and can do some
work on it myself.
Mine is 26', Some state parks limit the max feet to 28', another item to
think of.
I have towed a trailer with a canoe about 300-400#, no major problems.
I have set up my car to be towed (toad) but have not tried it yet. (Toyota
Echo).

Ed

After having a Jamboree class C on a Dodge chassis, we graduated to an
Airex (by Rexhall) on a Ford chassis, using the 460.  We did a LOT of
research before settling on this engine.  We excluded the Chevrolet 454
because we heard any number of horror stories about warped heads.

Since making our purchase, we have been very happy.  We have driven this
old beast about 60K miles, and it was eight years old when we bought it.
 There have no, count them, no engine or transmission problems other
than one leaky exhaust manifold (owing to an exhaust manifold bolt
breaking - and it was an easy and inexpensive replacement.

If possible, I would look for a 460 coupled with the overdrive-equipped
transmission.  That should improve the fuel economy by a respectable
fraction.  Ours is just the three-speed.  The old beast is 32' and gets
about 6.5 miles per gallon; the Chevrolet will do you no better.

We did just this very day buy a used Holiday Rambler Endeavor, wishing
as we did to move up to diesel.  Our fine old, reliable coach with the
unfortunately oxidized fiberglass exterior will now be placed on the
market.  That 460 has a lot of miles left in it.

Ken H