Darren,
I have the 40' version of your bus and LOVE IT!!!!!!! Look at my thread "Heavy Fuel". I intentionally went with a Cat engine. Yes, some don't like the Cat for various reasons, but I LOVE the Cat. Had three 3406B Cat engines that went well over 1 MILLION miles. Back in the day my '88 International 9200 had 1.3 MILLION miles WITHOUT a major rebuild. Did a cylinder head rebuild at 650K and she just kept on going. The other two I did a head rebuild at 800K and they went 1.2 million before I went belly up when Whirlpool left Indiana (another story for another time). Those engines went through hell and back more times than I can count. LOVE my Cat engines!!!! Put Prolong Engine treatment in the engine oil, Marvel Mystery Oil and Lucas in the fuel tank and PRESTO you now have a Cat that will go an easy one million miles. Change engine oil every month/10K miles and relax as the miles go by. I'm doing this with Heavy Fuel and her 3208 Cat engine as well. They replaced the engine with a Cat certified engine at 150K in California, so I now have a one million mile engine ready to run with. I know others on the site hate Cat (my pity to them), but when taken care of properly, they will last longer than the rest of the bus. Wife and I took nearly three years to find Heavy, but we're very grateful we did!
Hope this helps.
M