I got a 69 mach 1.

Looking to build a 390 FE I have into a monster.

If I put a 1x4 427 high riser intake and ported 427 high riser heads on it with a moderate street cam and long tube 427 headers on it what kind of horsepower do you think I could make?

Gonna bore the block 30 over also.

 

400 or so.

Do you have those parts?

Check this forum for more threads on 390 builds. Hot Rod did a build a while back and was over 400-450, but it was discredited here.

One thing to consider is a stroker crank:

www.ScatCrankshafts.com

There are other brands as well.

With your 4.080 bore & 4.25 stroke, you are at 444 ci.

The bigger displacement will bring the power on earlier and you can peak it out at a bottom end & valve train-saving 5500 or 6000 rpm.

Aluminum heads will allow a bit higher compression, so with iron you are probably in the 10-10.5 :1 area.

Anyway, there are several REAL builds running here, so look through this forum for dozens of examples.

 

Boy....... that could be 300HP to 650HP!? You didn't give us the details of your engine. Like valve size, Cam (Hyd, Solid, Roller), also cam specs, What rocker arms, What your heads flow, what carb, ignition set-up, your C/R and so on........ Don't mean to sound like a smart ***!

Also you will have to notch your cylinders for those heads, witch will limit lift of the cam too......