This subject comes up a lot on the FE forums and groups.  After reading all of the posts (including some from guys who worked in Flat Rock) over the past 25 years here is my take on the MCC FE blocks.  The nominal cylinder wall thickness is the same as the earlier DIF and CF blocks.  The difference is that the new MCC plant used robotic casting core placement processes versus the manual core setting used at the DIF.  Therefore the relative positions of the bore and water jacket cores were more precise than at the DIF.  So this means that MCC blocks (D3TE and D4TE) can "usually" be safely overbored more than a DIF block.  I understand why people assume that they must have thicker cylinder walls than DIF blocks but I am pretty sure this is not the case. I could be wrong but that is my humble opinion on this subject.

Factory GT-E engines were real deal side oiler blocks.  Everything else about them was early 428CJ ;-).

Here are some pics that I took last weekend at the FER&R if anyone is interested.  https://www.dropbox.com/sh/zxdn2rqhq1z70mz/AADof16oazZarhp9-B9t0uWZa?dl=0

Because Ford never had any intention of making the 428SCJ engine a performance upgrade over the 428CJ.  It came into being strictly to improve durability and reduce the high number of warranty claims that they were seeing from low geared 428CJ 4 speed cars out in the field.  My friend friend Kerry jokingly says that Ford should have called it the "Warranty Pack" instead of the Drag Pack option. JMHO

What I find interesting is that every $ forged FE/FT crankshaft that I have ever looked at did not have that half moon cutout in the flange. 

My dad loves to tell the story about the Hot Rod magazine article that came out in '67 where they took a 352 block out to 428 bore size and ran it on the Utah salt flats.  He said the next year everyone showed up at the drag strip with fresh "428ci" engines LOL.  All of them way over bored 352/390's. Dad said that every single one of them steam cleaned the exhaust system due to split cylinder walls before the end of the season.  Not saying that it cannot be done if the core shift is minimal especially for a cruiser.  But as Ross mentioned you still have pretty thin cylinder walls and ring sealing will for sure be an issue.  I say don't be cheap and just pay the extra $$$ for the real deal and then rest easy.  JMHO.  http://www.mercurystuff.com/articles/352_skiddoo_hello_428.html   

John, I think your right!

I looked on the mustangtec site and I found a CJ block that looks a lot like my block. They call it a '70 CJ block but, I think it started life as a Industrial/Truck block, with the boss and threaded hole, for the truck oil pickup and the plug for the compressor oil return.

http://mustangtek.com/block/1970428CJBlock.html

It also has no casting number, heavy C scratch and a date code like mine.

Anyone want to take a stab at what a W 1 or I means?

Yep that block on MustangTek is for sure an FT block.  No one knows for sure but the most popular theory is that the "W1" and "E1" above the date code indicate which casting line the block was cast in.

Edit:
After looking more closely at my 4 digit number, I think I see that same 0 with the same 2 dots under it so it would be a '70. staring at the second digit, it looks like it might be a G so, Sept and then, maybe the 16th.

If it's a DIF block engine when you pull the bellhousing and transmission off check behind the flywheel for a factory scratch mark on the rear bulkhead.  Very few FT blocks were cast with 428 water jacket cores but you might get lucky.  If there is no scratch mark it probably does not have thick cylinder walls unless it was cast in late '73 or early '74.  I used to search for FT engines/blocks back in the '90s and early '00s.  Of the several dozen that I looked at a grand total of 3 had scratch marks and 428 water jacket cores.  So they are not as common as a lot of guys claim.