How many of you would buy an aftermarket block in low deck height. Aluminum, cast iron, up to 4.500 bore size.

Excellent but one qualifier would be the remaining parent wall cross-section after it gets machined. A good sleeve can be .080 wall. All this said there weren't good rings available in 4.4 until about 4.430ish last I checked. I'll take a good ringed 4,375ish bore with the usual tricks over a 1/16" ring 4.420 bore any day. Another sleeve possibility is if you could thread the block and sleeve. Depending on the ability to machine and create this 'superblock' It'd be a good idea to offset the mains for a 9/16 stud and ring dowel both fasteners for a custom alloy cap. After the lifter bores were properly bushed and indexed should be a solid foundation for 900HP...
Thanks, that is true about ring availability. Great advice in there too