You may have seen this already, but the Shelby Engine Company has added an aluminum 289 block to its line-up to join the 351 and 427. It is a direct bolt in replacement for the original 289 blocks. Here are some details:
The Shelby Alloy 289 Block is much lighter and stronger than the factory cast iron version. The Shelby 289 block is fully CNC machined. It also will feature a casting number similar to the original 289 HIPO blocks.
Shelby 289 Aluminum Block Technical Features:
Block Material A356,T6 aluminum Blocks is CNC machined
Deck Height 8.2-inch
Deck Thickness 0.750-inch
Cylinder bore range 4.030-inch,std.,to special order 4.155-inch
Maximum Stroke 3.4-inch
Displacements up to 368 cubic inches
Cylinder sleeve Centrifugally cast dry sleeves
Cylinder wall Siamese with dry liners
Main bearing cap Billet steel
Main bearing cap bolt
configuration studs;4 splayed bolts on 2-3-4 mains
oil sump Accommodates wet or dry sump oiling systems
Head stud diameter 0.500-inch
Bare block weight 90 pounds, approximately