You have a great platform to build for a 5 cube class, and where you compete may or may not have a 5 cube open class. If you are building it for the 5 cube open class that's fine. But, if your competition is already showing up with 7.26 cubic inches(or more) you may want to look into buying something with a little more size to it and start there. Almost everything you learn on the 5 cube can be applied to the larger saws.
One major thing I learned is the larger bore saws are more susceptible to damage due to making the exhaust ports too wide. My first 3120 (years ago) was idling in the parking lot of our shop after coming off a strong finish the following year. It was entering its second year of competition as it sat there idling.......then it suddenly stopped and it spit pieces of the piston out of the cylinder. What was happening is, as the ring passes by the open exhaust port, the ring will bulge out a little in to the exhaust port, then it will go back towards the piston as it passes the upper(roof), or lower(floor) portion of the port. It only does this a little bit, not much. But in my case that port was a little too wide, going back up its last time a ring struck the roof of the exhaust port and took out the whole top end. There is other port shapes that will help keep this from being a common occurrence, one would be an oval shape, but once you are too wide, port shape will not be there to save you.
My recommendation is to work on displacement before you go further if you are running other saws that are not 5 cube. If there is a 5 cube class keep working on that one and pick up a used big saw if you can.
