I like Ray Borrets old saying when the last Bathurst Group A Commodore got NASCAR spec rods.
"We went to the racers with a grocery list of parts. They focused on rod breakages at 7000 rpm plus. Power is torque times rpm. If you want more power, find more revs!. .......we went to what was basically a NASCAR beam Chevy rod to cope with 8000 rpm "
I'd look at big ports, stick with the current block, and just run rods and pistons which will hack 7500 rpm.
For me, it would be a constant supply of aftermarket alloy SBC rods of the common 6" or , if your brave, some local (Ridgecrest?) item to drum up local business.
I'd use the Subaru forged pistons, which have the 0.945" pin, and see if there is a blank which will give you an SVO pistons A3 head, 12.5:1 style dome to fit the hemi head. Its basically like setting the bump on a diesel or Hemi 426, because you need 12 to 15:1 compression, and the AU head suits the fuel better because it allows a large amount of spark lead before torching down cylinder walls. I'd stick with the 3.632" bore.
Run a wild custom cam grind, and keep the VCT system. You could run the VCT via an ABS cut-out ring, and when the slip speed exceeds 15 km/h, run an alogorithim to wipe off cam advance.
Why not do the dirty, and grab two Cal pak Holden computers, and bank fire 12 injectors off two computers? 6 in a stock EB intake runner, and 12 upstream for added fuel. Run the same kind of plenumb as Dynoed 250's, but spend more time setting up and elipsodal cover where his was cut out.Run stub stacks, and run it off a MAP sensor. I favor the slide throttle systems, but why not run two MAP sensors on each end with two throtle bodies runing two computers. Geeze, the Delco system is so easy to tune, and alcohol injection has fuel delivery problems. Most people are so slap happy with the aftermarket systems becasue they run cobnstant feed systems, and over supply there blowers. Others just use carbs. The fuel load for a 500 hp engine is well over 27 cc per second for a F1 engine. On methonal, it goes up 1.57 to what, 42 cc per second. Why not just use twelve 360 cc Magna injectors, and pickle the engine with methonal.
The cheap bit is that most people can never afford all the right stuff in V8's. In a six, there is the common Subaru piston, Chev rods can fit, and you can blow up as many 100 dollar AU blocks you can find without crying into your beer.
Mate, if you can cam, fuel, and rev it, it wont miss two extra cylinders!
If you want an adaptor for a SBF V8 pattern C10, C9, or C4 to fit your Altered, and dont mind a right hand side starter mount, call me on 643 4535 668 and leave a message. I'll add an adaptor into my business plan.
I'm getting my adaptor business sorted out here, and I'd love to offer help a bloke form Peeerth!.
! OO6./The-X-Or-Six!