Hehe, it's not NOS. I could have put NOS in it, but I use that big tank when I go to shows to play around with the cylinders (I don't use airbags to make it move around/go up and down), so it's a tank I fill up with either Helium or just air. It has a built in compressor if the tank runs empty, but I normally keep the tank full.....and in the floor board. I'm too lazy to take it out haha!
Don't discount 5 hp. Its like 5 extra 1,000lb beasts hauling your butt down the strip.
But you would be amazed what you can get out of a good block with the right pistons and heads.
I do see the appeal and recognize the work and effort you put into that car though. Still, I think you won't get your $$ back, but none of us really do I guess anyway.
RTR
Oh I know I won't get anywhere near my money back for it hehe, but something is better than nothing.

I remember putting a 454 in my friend's truck when we were teenagers.....holy mother. You could literally watch the gas gauge go from full to empty or simply be going down the road at 60 MPH, stomp the gas and burn out. Was a lot of crazy fun.