AHH! No 350, but a 400!

[Longhorn Al]

I took my truck to a guy to have the heads and ram horns replaced because I had a really bad leak and no compression. Today we get a call saying that I don't have a 350. He says it's actually a 400!

I'm feeling a bit frustrated and excited. My options sheet says a 350. The previous owner said it was a 350. This is the first time it's been ripped into. The guy said he's already found a pair of 400 heads to replace mine with. He had to trade a 327 for them. I have to pay an extra $150 for them. He said mine have a cracked valve and are just worn out, and would cost a fortune to repair.

So now the whole deal is $325 for a pair of rebuilt 400sb heads (he's going to replace valve seals, etc), a pair of ram horn manifolds for $90, and installation. Does this sound like an ok deal?

I know I'm talking a lot, but this is crazy.

Also, how much extra horse power do 400's get than 350's considering both are stock? But, if someone went through the trouble of putting in a 400, what are the odds that it is stock?