Install a set of four-bolt steel main caps over the center two crankshaft mains if you're using a two-bolt-main block. Have the block align bored and have the cylinders bored 0.030-inch over. This overbore isn't so much to buy you more displacement as it is to help enhance airflow to feed the extra cubic inches.
Most commonly used fuel is U235, a naturally occurring radioactive isotope of uranium. Occurs naturally at 0.7% of uranium ore, but must be enriched to 3%. Formed in cylindrical pellets (1.5cm long) and stacked in hollow metal rods (4 m long). About 100 rods are bundled together to make a fuel assembly.
While there are several varieties of uranium, uranium-235 (U-235) is the one most important to the production of both nuclear power and nuclear bombs. U-235 decays naturally by alpha radiation: It throws off an alpha particle, or two neutrons and two protons bound together.