If you have the money, the performance you'll get from the aluminum heads is far better than the iron heads will give you. The aluminum will be less likely to produce spark knock,
My thoughts on the valve tip broken is it happened at the machine shop. probably didn't have the tool centered and it caught the end of the valve, they usually have pneumatic spring compressor, I have used 273 adj rockers on a hydraulic cam 340 with off the shelf standard length pushrods. There is some valve train noise,you just hear things moving,probably 15,000 miles on the build so far. it will be hard to get a quiet, factory like noise level. expect some noise.

I think a new set of valves,lap them in, good to go.