Bill, the piston thing was meant as a joke... in no way, shape, or form was I the least bit serious about pistons being the cause of detonation. Just my dry way of humor I suppose...
Yes, I know you said 1200-1500, I'm saying 1200 is more the upper limit from my perception, and the local jokel may do a porting job (If you trust him, and he has a bit of experience and a flowbench) for a little bit cheaper than the big slant guys charge. And with the valve like you talk they may still be able to get 200cfm, or at least close. I weren't meaning to give you too hard of a time!
Yes, I have done a little bit of porting on my own head. I've got it tore apart now and am doing a little more. Who knows of it'll even go back together... You need some long burrs, I mainly have just worked on smoothin the bowls, narrowing around the valve guides, gasket match (you'd be surprised how the gasket lines up... or don't...) The cast iron means work is slow, but a little more... Forgiving? It's harder to get ahead of yourself and really bugger something. Plus, mine is the later 'peanut head'. Heaver, but thicker and able to be opened up more.
Also, one of the things
I was getting at: The less boost it takes to reach this goal, the cooler the charge, and the less you should have to worry about detonation. Maybe even get away with stocker pistons if 10lbs or under. (Though I would still buy these as an insurance, especially since all slants that came in A-Bodies are forged and have forged rods; K1/Molnars are overkill for this app.
https://www.flatlanderracing.com/hpkits-chrysler.html )