Bigger is not necessarily better, especially on cam and heads for a low rpm street driver. What works on the track at 7,000 rpm can be a miserable pooch idling around town at 2200 rpm...

IMO, it's best to build for torque on a street engine, and let the horsepower numbers fall where they will. Heads with big valves and big (over 185 is a waste)long duration, high lift cam, on the street just won't build torque at streetable rpm levels...... and if he's running the old dinosaur 2.02 chebbie cast iron heads and a big nasty rumpity-rump cam on his daily driver he would in fact have better STREET USABLE performance with a set of 1.94 heads with about 170-175 runners......

PS---You'll never settle the debate..... Guys read and hear only what they want to hear about what works and what doesn't... Sounds like your buddy is of the bigger is better line of thought and will probably stay there......until he gets dusted by somebody with a properly tuned but stock 5.0 Mustang!!!!!