economic 318 aftermarket heads

wasnt there a company that was making new magnum style heads in the LA configuration? They were magnum heads but used the LA style intake bolt pattern and pushrods....???

Aerohead has 318 heads for 399 a pair. Why are the 340-360 heads 100 more when they have the same valves and chamber volume?

Will I lose power by using those? What is the advantage if the vol. and valve size is the same....??

I thought 360 heads were significantly larger vol. than 318 heads.... so are the 318 heads that aero lists really a 360 head?

Sorry for all the questions