Your situation is one that we (MH owners) all will probably have to face.
I agree with your assumption that gasoline (and diesel) prices will inflate in the near future.
If we are talking strictly gas engines, in my opinion, a fuel injection system will be more fuel efficient, all other parameters being equal (no emission constraints).
Your 310 probably does not have a computer, to go with FI you would have to procure one (salvage?), and have someone tune it for the MH application.
In my situation, (close to 16,000 lbs, with a sometimes toad), I need all the power the 454 puts out at 3000 rpm at 60mph. This may or may not be too fast for the 5.9 liter cummins (my personal diesel engine of choice....lots of 'em, they do fit into the engine compartment, weight fairly comparable to the 454). So.....depending on your rear end and torque/RPM requirements, an overdrive/underdrive may (or may not) be an additional investment.
Another thought (concern?), even with gas at $3.00 per gallon, you'd have to drive a bunch of miles to justify the initial expense of converting to diesel.
Be sure to go with a header/exhaust system tuned for MH applications (max efficiency 2500 to 3200 rpm), and eleminate all the intake air restrictions you can. Banks makes a good system, but certainly there are others available.
Good luck! Please keep the Forum posted on your decisions, progress, and results.
We're all just the proverbial "one hard hill pull" from your situation.
"Suck it up, spend the bucks, do it right the first time."
WBCCI # 1113
Trailer '78 31' Sovereign
Living Large at an Airstream Park on the Largest Lake Totally Contained in Texas
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