My Initial 553 build

I am in the process of figuring out the best engine build for my needs. Which are heavy snow removal and towing with my 1979 ford bronco. Low end torque is the goal. Engine will probably never see 5500 rpm, 95% of the time 3000 rpm will be the upper limit. 6000 pound bronco (with 460/553), 350 gears and 35" tall tires, C6 automatic(build later), locking differentials.

So far:
E85 fuel being used as primary fuel...Propane will be added to the system as an alternate( I do NOT care about fuel mileage) Reasoning...E85 is not sold everywhere and having a backup fuel will get me to the E85 fuel station. I have a 1974 Lincoln 460 (Stock) in the bronco now and have power issues when all differentials are locked and trying to push or pull anything really heavy.

SCJ aluminum heads 72 cc
Diamond Pistons (flat tops) with 13.6:1 compression
6.7" rods (unless Stock 6.605 rods would be better for torque) would have to change CID or have custom pistons made
Forged steel 4.5" crank
Deck milled to .005(10.005")
.045 compressed head gaskets
Need cam recommendation....one cam company said Extreme 278 series
Carburetor recommendation also needed
Stealth SCJ intake manifold

Any suggestions?

I have found with heavy towing if you go over about 10-1 with propane you are looking for trouble. I now run about 9.3 and engine is happy. Propane does have detonation resistance in an unloaded apllication and is great but under heavy load you will have issues.

JMO Mark

Use the CJ, (marine), cast iron manifold NOT the Stealth ... 13.5/1 compression is to high for a highly loaded, low RPM engine no matter what the fuel ... get a custom cam for your application; (one that will have high torque yet compensate for extra loading and curb any detonation).