Check your engine oil level faithfully Rob, especially when a hot engine under load has the oil thinned out. I have a feeling all that vacuum is going to suck raw oil right into the intake. The only place to go after that, is out the exhaust.
I don't have it near the desk here to confirm, but I thought there was an oil-bath air cleaner in our KAMA parts manual. If you're considering one, remember that the loader frame on that 554 had a pass-through hole to accommodate the intake runner.
//greg//