915 J heads, need specific machining details to squeeze as much as possible out of them

I'm betting we can drag this post out to 3 or 4 pages before he goes with aluminum heads & junks those cast iron things.
Probably.
But I'm weighing the same decisions except my J-heads are already on the motor. I tend to like to use what I have. I might even take a swipe at carving on them before I go the next step. I'm not going to dump a bunch of money into them just to prove that it can be done though.