Complete rebuild 454 ??

[Rnd]

1977 GMC C2500, 2wd, 3+3, 4.11 rear, 700r4 trans.

I replaced the 400 THM with a rebuilt 700r4. Now it's time to refresh the engine.

I started out at about 12 (11.7) mpg before trans replacement I'm now around 15 mpg.

When traveling at highway speeds 70 mph+/- it has very little to no power/torque to climb hills etc.. With the overdrive and lock up I've taken the engine out of it's power band. For those that remember. The 70's were not good years for the automotive industry....Oil embargo, emissions, federal speed limit of 55mph, unleaded fuel, and limited technology did not add up to very good performance....

So my question/questions...I have a stock 454 mark 4 with 71,000 miles. (Numbers matching stock engine.) I'm going to do a complete rebuild but don't know what components to use????

Looking to increase low end torque yet preserve fuel mileage.

Primarily I would like help on piston and camshaft recommendations.

Also I could use some help on what cylinder heads I may have. (round ports or oval) and what is the difference?? I really don't want to buy new heads. That would kill the rebuild and send me into crate motor territory.

Offer up some ideas,,,, Please.

P.S. Would like to hear from the guys that have done a few and know the pit falls.

Thanking you in advance, Randy

[BigBlocksRule]

You'll want oval port heads - they're the "middle" of the 3. Smallest is "peanut" ports, great for towing but run out of air early. Largest are rectangular ports, good for racing but not the best choice for the street.
Best ovals are castings that end in -781 or -049. Leave the valve sizes stock, don't need bigger ones at this point. Have the castings cleaned up in the bowls and runners and the bowls smoothed. Shoot for compression in the 9:1 range, will require a small dome piston. No need for a fender shaking cam, something in the 220 - 224 range will be fine. Dual plane intake and headers.
And buy stock in a tire company

[bnoon]

You will have peanut port heads for sure if they're stock heads. Don't worry though, they're fine for low end grunt and will even make decent power with a few modifications. I would concentrate on something around a .500-.520 lift, on a 112 lobe separation (for MPG) in a split pattern with the concentration being on more lift/duration for the exhaust side. 1.75" headers and a Summit Racing Stage 1 (or stage 2 if you swap to square bore carb) intake manifold. Aside from anything needing replacement during the rebuild I think that would be it for the bare bones basics. It's kinda where my truck is now for engine mods except I don't have the intake manifold. I'm aiming much higher myself though. Pro-Comp heads, big cam, big headers, etc.