Never heard of "bronzed" pistons. Your friend is probably dumb and talking about thermal piston coatings(IIRC, most are ceramic). They do not help much at all with detonation unless your piston has hot spots. Air/fuel tuning and combustion chamber design will dictate whatever detonation you'll see.
The layer of carbon that "naturally" builds up on the pistons do the same thing as thermal coatings; which is reduce heat transfer to the pistons and increase thermal efficiency; in other words people use them on "low-mileage" setups to make more power. Mainly race cars use coatings because they aren't driven long enough to build-up that layer of carbon on the pistons, unlike street motors.
You will most likely punch a hole in your block; then again some people have got away with it(wet shot with something that'll retard timing). If the block is built and setup is tuned; then you'll most likely have no problems running a shot that large.