Is there anyway to change the rods and pistons from the bottom (oil pan) without pulling the engine?

 

Planning on starting with around similar HP levels so I will just ask a question in your thread as well.

How about the oil pump? Should it be okay around those numbers or would it be wise to change it? And how about going for a double roller chain or are those mods more if you plan on spinning the engine at higher revs? And if so should you keep below 6500 or what is "safe"?