double hump heads on a 78 engine

[sk8er32283]

I have an opportunity to buy some double hump heads #461 for about 400 bucks. Here is the info in the ad.

I took these heads on trade. They
have been rebuilt with 2.02/1.60 stainless valves, double valve springs, machined for screw in studs. They have not been run, I do not know specs on springs, was told they have hardened seats but it is tuff to tell without removing a couple of valves. They are casting 461 and should be 64cc chambers. I do not know who did the rebuild.

First question is will they work on a 78 350 engine and will it up the performance a lot or just a bit. Second question is that a good price for those heads. Any suggestions are welcome. I don't know much about heads except that theyear have a smaller chamber that will up the compression ratio a bit and help in the horsepower department. Thanks guys.