Not trying to pile on here, but several years ago i posted an issue a real good friend of mine had with MM doing a " stage 2"port job on a set of eddie heads that resided on top of his 408 motor they built that was 12.5 to 1 compression that was a dog at the track( high 11's with pretty darn good combo).

I took the heads off for him and had them sent to a well known mopar builder on here. He looked them over and said basically nothing had been done to them..just shined the intake ports a tiny bit and removed no metal, to make it appear they had been massaged.He was far from happy with the valve job also.
This guy ported the heads to the level my buddy had expected MM to have done in the first place, and the car goes 11 flat on a 90 degree day up here in michigan..6 tenths difference!!!! from 113 mph to 120.This was first time out with it.

They finally did make some sort of restitution, i honestly dont remember what it was now,this was about 4/5 years ago...but the point is, he was charged for work that out and out wasnt done in the first place. So, i am not really surprised to read this post and others...its frankly a continuing saga with MM.
Its a real good reason why i have taken any motors i have had built over the years out of my immediate neighborhood( i am very near MM) and had the work done elsewhere, where i had nary a lick of trouble, either at Hensley or Best Machine.
Both of whom i would recommend to anybody.

Edit..in fairness i should mention my buddy was running a 750 on his combo that i had him replace with a 950 from summit( just a box stock proform unit i sat the float bowls and idle on for him prior to that outing, nothing more) i suspect that accounted for maybe 10-15% of his ET increase, but not a solid 6 tenths and 7 MPH. The combo was otherwise identical to what he ran previously. just the head work, new valve job and carb change.