As was mentioned, whether the 100mm crank is used in a 63 or 64 block, the rod ratio should be the same.
2.38 is 2.4 just like our 1.99's are 2.0's.
Anyhow, here is a nice little chart to use as a reference in regards to displacement. The pistons I'll more than likely be getting are 40 over (86.5mm) which when combined with the 100mm crank, show that I'm sitting closer to 2.35 (which does round to 2.4). So switching to a 4G64 block really won't net me .1L more. I can get that same 2.4 if I just bore it out further. The 4G64 is a 2.4 because it simply has a larger bore...
Again, I've done the research on the motor itself. What my question was, is this a good idea considering the rest of my setup. Just want to make sure that with the added displancement and airflow I'll be seeing, will I actually lose power or anything because I'm choking it. Maybe my setup works great on a 2.0, but add that extra bit of displacement, just want to make sure I'm going to kill my setup.
Thanks for all the feedback so far though, keep it coming! Right now I'm just trying to locate some pistons.