For the Motor Gurus

[63longfleet]

I am putting a 350,700r4 combo in my 63. in taking the enging apart to change manifold, cam, etc i got the casting numbers off the heads 462624. All i have read says they are junk prone to cracking. BUT i also read that there was a heavy duty (not a thin casting) version of this head also, The motor i am using is out of a boat and is a 260hp Mercruiser. I dont know if that makes a difference or not. Any help or advice would be greatly appreciated