Wow a couple interesting posts here

"you will gain at least 100 hp. the competition cam will provide power, reguardless. they are good at that. with flat tops and 10:1 compression it will hunger for 94oct on hot days.

im maybe thinking, its making advertised hp 450.

horsepower @ .050 350hp. "

Make that about a 25hp difference in the stock 360LA heads VS the magnums. You will gain some tq and MPG from them also I have no idea what HP @.050 means so I can't guess at that but depending on what a "small comp cam" is 400 hp should be a piece of cake. The XE268H would be a good choice, it is basically a step up from the factory 68 340 4spd cam. It will make decent vacume and a factory high stall converter will work great.


Also there is this,

"My heads are also the largest valved of the 3 encarnations that came from the factory."

Don't worry about valve sizes, magnums only left the factory with 1.94 1.625 valves. Combined with there 5/16 stems they flow every bit as good as an X head with 2.02 valves. There extra power comes from effiecncy They will out power factory 1.88 valved 360 heads by a bunch and will flat kill a 318 sized 1.75 valved head.