Looking for help I currently have a 1990 454 stroked to 496 with Eagle kit
but my heads are still the peanut heads and stock cam

looking to swap the heads out with the 420 merc heads witch are merlin 043 rectangle heads

currently my compression is at 10.1
will these heads work for me I'll also be taking the 420 intake as well I have kodiak aluminum manifolds as well please help out

they will but you really need more cam,like crane 731

x2 and then some. What max rpm OP? Get a single plane for a couple hundred bucks or eddy air gap. Many Holley 800 9022 carbs etc for sale on swap. Would kinda complete your build very reasonable.

There was a very clean, almost new 800 cfm Quick Fuel (New Holley technology) carb in the swap shop at a great price. (The 9022 is the older Holley version of 800 cfm).
You will love the upgrades. Good luck.

So then heads would work for me ?

Also yes I will be getting an 800 double pump does anyone know roughly what the horsepower would be of that motor with them heads and cam with my bottom end

Stock cam ?

897.8231hp

Going to need some boost for that

In all seriousness about 500+ hp, (unless you buy your parts from JC Whittney catalogue).