What do the spark plugs look like? If it's running rich, they will be black and sooty. Proper mixture and good ignition makes plugs have a tan to chocolate brown color with no noticeable deposits. Long duration cams have a tendency to run rich and/or waste a lot of gas at idle, so unless something other than the exhaust smell indicates you've got problems you could probably get by "as is".
Like Evan has said, doing some dyno runs is going to be the only effective way to make a high performance engine work anywhere near right. Before an assistant principal at the school where I taught discarded a file cabinet full of records by mistake, I had a couple of hundred hours' worth of documentation of dyno runs on small block Chevy round track racing engines my students had built for the 5/8 mile NASCAR short track at Nashville Tennessee. Two local car owners supplied the funding, and my students built and tuned the engines. The kids who were at least 16 years old got to be on the pit crews during the summer racing season.
Jerry
