The Shelby 427 block is NOT a center oiler or top oiler. It has a priority main
oil passage that runs next to the camshaft. This passage feeds
oil directly to the main bearings from the
oil pump. A factory 427 side oiler does have a separate main bearing oil passage but the oil still needs to feed around the outside of cam bearings (through grooves cut in the cam journals) before it feeds down to the crankshaft. The reason the oil passage was placed where it is in the Shelby block is if someone ever broke a connecting rod (heaven forbid!) and punched a hole in the block the aluminum could easily be reaired and it would not be necessary to attempt to fix the oil passage on the side of the block. Also theoretically the motor would not loose the oil pressure lost from punching out the side oiler oil passage. The priority main oil galley is in the same location as all the other aftermarket Ford and GM racing blocks. I have my own Shelby block and have built 2 417 Arias/Donovan hemis and can tell you catagorically the only thing these two blocks have in common is they both have 10 head bolts and 8 big holes arranged in a "V"
The Arias Chevy has strengthening ribs in the lifter valley as well.
Maybe it was built from the 417 too! ALL standard FE parts
(except for a stock starter) will fit on the Shelby block. As for the original question that started this thread, Yes you are correct.
If you are having an engine built and you have to pay $4000+ for
an original side oiler and all the other components are the same,
it will only cost you $1000 to $1500 more to build the same
engine with a Shelby block.
HTH,
Mike