Ls-R is a canted valve head like the Mast Mozez head. The are very nice pieces.
And Capable of flowing 435-450 CFM in the right hands, these LS-Rs flow between 435@.700 and 440@ .800 and 450 @ .900
Thitek heads can get close in the flow department.....Edelbrock G3 heads will never get there, they are lucky to get in the 390/400 range@ .700.
That 475LS is close to a 55k as tested . the block is 9.75 Deck height....... 4.155X4.375 , and a LOT of internal work to make that 4.375 crank work in that block, fitting a 4.10 stroke crank is lot of work....... it's also uses 6.46 C to C rods, Pistons are 1.10 Ph height , Rod Ratio is 1.47 . uses 2.25 Intake valve with a Valve to bore ratio of .54 ....just right for canted Valves.
Crank is Callies LS Ultra Billet 8 Counter weight 4.375 stroke. the off the self 4.0 stroke version of that crank cost $32XX, you will pay less for a new Callies G2 Hemi block then you will for that 4.375 stroke crank shaft.
Block is Dart LS Next Tall deck $4700......which is still less then the crankshaft used in that build.
the CID Intake was close to $1500 and is a custom piece at this point.
lets not get into the rocker gear...it's about the same as anything Reid for a G2 Hemi.
Biggest LS I've ever done was a 481ci 4.185X4.375 with CID Oval port LS heads with raised Exhaust which flowed 425@.700 and 435@.800 ....total cost in parts was 38k ...again price for the PARTS was 38k and made 990hp with .8XX/.7XX 255/260@.50 on 112oct
the Biggest G3 I ever built started out as a 2014 BGE block it was machined to use Darton LS Sleves , and hard blocked for the 1st 2.5 inches..... 4.20 bore with a 4.30 stroke crank for 476.5(lets round up and say 477) 6.125 rods , so rod ratio was 1.42 pistons were Hockey pucks 1.00 .....it had Thitek heads and .630/645 240/245@.50 cam 114CL made just shy of 875 on pump gas @ 6800 pulled it off the dyno , sent the crank and rods out to be magged and the crank came back with stress fractures.
now to get the 4.30 stroke I had to offset grind a 4.25 K1 crank, to 1.88 journal size. Lots of grinding to get the crank to fit, the oil drain cross tube on the passenger side rear of the block had to be taken out BIG clearance notches Everywhere... .total parts cost was 14k ...yes 14k , Block was 1300, Crank was on sale from TH motorsports for $650, rods were Pankl 1.88 BE bore with .797 pins .rods and heads were the most expensive part of the build roughly half of the cost , the darton sleeves were a buddy buddy deal and cost about $750 , the machine work was costly had to sign a waiver to get the guy to do the work....I honestly don't blame him. I hard blocked the bottom of the water jacket to insure stability didn't want to take the chance of the sleeve moving around with that much side loading.....Pistons were some where between 1000 and 1200.
at this time the aftermarket parts to build the Equivalent G3 Hemi to this 475 LS(X)....do not exist......and considering how 90% of the G3 performance "enthusiast" lean towards Boosted applications and the EPA's war on anything "performance" I doubt they will exist.
At this point we really only have one aftermarket block which you can get in a 9.75 deck height if you go solid billet with no water jacket. but if you want a water jacket then your limited to a 9.28in deck height. which limits us to a useable 4.25 inch stroke...... ......and you can not make enough clearance in the stock blocks to use a crank over 4.3 inches. realistically for NA we are limited to a 4.165 bore with the BGE blocks , 4.125 to be on the safe side. Now the 6.1 block , Darton makes a sleeve that will go to 4.165 but the 9.24 deck height limits stroke to a max of 4.25 and here again you end up having to use a 1.00 Pin height to fit it all in the cylinder which is fine for a 500mile Nascar engine , lousy for the boosted crowd. and not daily driver friendly.