Sal,
The welded "C" on my block was kind of cursive and could resemble a "G" but it all checked out.
I strongly recommend you use a good reputable "FORD" engine builder. Be sure and use quality parts and be certain to have all your clearances correct. Use
oil restrictors in your heads. Balance your engine and you should be very happy with your build and performance. By the way if you need a newly built original expansion tank I have one that George Anderson of Gessford Machine built for me I would make you a good price on it.
Clois