I have struggled with the same thing since these heads were first in design years ago by another company that let them fizzle before Murment took over.
I have a 312-4 (D) engine in the 57 T-bird, when we stopped showing the car to drive it, one of the things I did was pull a perfect low mileage and never rebuilt engine and tried to beef it up, the block showed it could handle a 120 boar, so I punched it out 80 thousands, slight milling of head and a high low rpm torque cam and had the heads ported, gave away the original carb to someone I did not like. (LOL).
Never did buy the heads as the Y’s are low RPMs and I just could not see where, I was starving for air or what good the extra rpms would do, as my mission was to make a reliable car wife could drive anytime she wanted or we could take on a weekend trip.
Of all the things I did to this car the thing that changed the car the most was taking out the fordomatic trans and putting in a mild beefed up AOD and at the same time, took out the 3:10 rear end and put in a 3:56. OH, gas milage went from 11-12 to 19-21 also.
Different car totally and it will run with a new GT stang up to 60 with no problems (well as of 2 years ago, not sure what they have in the newer ones.)
Cost of the AOD swap was around $2500 and it took me about two months as I was the first to do on a T-Bird X frame and everyone said you would have to cut and I did not have to cut but paid the price in the amount of time it took.
My plans were to do it on a weekend, good thing I don’t write estimates for a mechanical shop!
Since these heads are known to acquire cracks and over the years I have replaced one and repaired the other, if they ever do crack again, then I will buy the Aluminum heads but that would be my only reason.
Hope this helps!