That's about right although you might get them a little cheaper somewhere else. You may already know this so I hope I'm not teaching you to such eggs but It's been recommended to me to at least use a GM timing chain and if you want to you can use a FAI balance chain. It's a bit of a trek from you but I can highly recommend @[deleted] to change your chains for you. He's a really great guy and he knows these engines inside out, he did mine and I travelled up from Surrey to him (about 170 miles each way). I was quoted £900 by a cam chain specialist to do mine, but I got them done a lot cheaper and had a weekend away to boot with the wife, lol. If @[deleted] is still doing them through the shop on the forum then maybe have a chat to him. I know prices have gone up but he got mine (both genuine chain kits with all the bits I needed) for slightly less than that. Have a look here, bearing in mind that you'd need other bits as well.