[undy]

I read it as a C3AE-6015-H. It's a regular, nothing special 63 390 block. That (may) sort of support my original statement about the cross-bolting being and aftermarket modification.

On the other hand, there are several posts with 427s having the same casting numbers. Get a ruler and measure your bore and get back with us.

http://www.mustangtek.com/block/C3AE-6015-H.html

http://www.dragtimes.com/parts/19636...735729624.html