I just caught rhe part about pumpgas. Seriously, you need cubes and airflow for that . What parts do you have to throw at a 4.5 bore aluminum block? Maybe $ 6600 to get one in hand (BME) , ready to assemble, and750 to 800 pumpgas hp will be a whole lot easier to do. The block should turn out to be a one time investment, and 100 pounds off the nose is huge . How much would it cost to replace two broken stockblocks? A lot more than just blocks and machine work.