Only repairable if you can find someone that can repair the aluminum. Usually they get scrapped because it' very hard to find someone to actually fix them. Most places will not touch an aluminum head to repair.
Cast iron has more potential to make more horsepower and last a very long time...
http://www.campbellenterprises.com/engine-rebuild-kits/stroker-kit-rotating-assembly/stroker-kits.htm
I got my 340 stroker kit from here with the forged molnar tech crank,mahle dish pistons and h beam rods