Thinking of upgrading from a 7.4 to a 8.1 Gasser

I love my 8.1 and have put 56K miles on it in 7 years. It does want a quart of oil every 3K miles or so. My brother, who rebuilds his owns engines and such and who has an 8.1 Yukon, tells me that having the spark plugs replaced by a professional at 100K miles is a MUST.