This seems to be the Product : So Figuring Block machining , Dart Cly. Inserts plus Actually assembly of said -
Darts into a Block = $2000.00 easily-Plus Shipping Fees & Dis-assembly
- Plus Re-assembly !
This Product might just be able to
Stabilize the Cly. & Support at the Critical Area - as shown in the Photo . This would be more like =$200.00 Bucks + less time and Shipping Fees
still would might have some basic machining of Block to flatness & New Water Jacket Opening , so It would cost possibly $400-$500.00 .
It's a Theory , but based on good Info - in fact If done on a Flat - Non - Stick Surface ( Up side Down of Course ) a Good man with a Router could Finish it off - back to $200.00 Cost .

Time .
http://www.alvinproducts.com/Products/Products.asp?id=2
Now that said : I say this would be a 430 HP area , Not - 500-600 HP like You could go with the Darts .
I'm being Conservative on 430 HP .
Here's the Spec's :
Description: Ready-to-use aluminum filled repair and patching compound. Single component dent and body filler.
Color: Metal gray. Aluminum when buffed or sanded.
Adhesion: Excellent adhesion to clean, dry surfaces of metal (aluminum, steel, stainless, brass, bronze, cast iron, copper, lead...), wood, hard plastic, and glass. No heat needed; hardens upon exposure to air. Please note: Lab-metal will not bond two parts together; Lab-metal requires air in order to dry.
Hardness: 81 on Shore D scale
Coefficient of Linear Expansion: 15 x 10-6 inch/inch per ºF
Strength: Tensile: 650 lbs./square inch
Compressive: Approx. 20,000 psi
Water pressure: 50 psi
Specific gravity: 1.95 at 75ºF
Weight: One cubic inch: 31.2 grams or 1.10 oz.
Heat resistance: When dry and hard, withstands temperatures to 350ºF and is not affected by cold to -40ºF. Withstands higher temperatures (up to 425ºF) if heat exposure is less than 20 minutes. (For prolonged higher temperatures, Hi-Temp Lab-metal is available.)
Chemical Resistance: Not affected by mild acids, gasoline, petroleum, petroleum solvents, oil or L.P. gas. Alkalis will attack Lab-metal slowly, but only after extensive immersion.
Combustibility: Dry and hard material will not support combustion.
Conductivity: A non-conductor at normal voltage. Not considered an insulator. Accepts ground for powder coating.