I am in the process of building a 468 big block. The parts: 454 block, 0.060 over Stock 4.00 stroke cast crank Stock (reconditioned) rods with arp bolts Keith Black Silvolite Pistons, about 9.2:1 compr. Weiand Stealth Oval Port Intake Comp Cams Xtreme Energy hydraulic cams with about 0.515/0.530 lift I am not sure about the heads as i want to build the engine mainly for torque, but a little top-end powerwould not hurt. My budget is tight, so aluminum heads are out of reach. The candidates are: World Product Merlin (oval port, 269 cc intake runner) GM 188 or 990 castings (rectangular, 317 cc intake runner) Several sources on the net say that the Merlin (even with smaller runners) flows a little bit better than the GM head, on the other hand, the GM castings are hard to beat price-wise (about 480$ ea vs. 650-700$ for the Merlins, both ready to bolt-on). The Merlins have a bigger 2.25 intake valve (GM: 2.19), exhaust is identical with 1.88. Now my question: Are the differences in flow really that significant for a off-road vehicle? Has anybody experiences with one of these heads? Will the cast crank hold up (projected power level: 450-500 hp) ? Any help is appreciated! Thanks in advance "DO IT TODAY, TOMORROW IT COULD BE ILLEGAL!"