Looking at the Suburban link. All those will require new cylinders.
There is no way to take a 117 inch motor, and make it have more displacement, which is more cubic inches with out doing one of two things. The first and easiest is bigger cylinders to accommodate bigger pistons, the 117 to 124. The other option is to give the motor more stroke.
It is possible to put bigger cylinders on and still have a highly reliable motor when done with the right parts and the right builder. Key is all parts designed to work together, compression low enough to keep cranking pressures close to stock.
I am planing to take my 19 CVO Road Glide to 130 inches. I usually take two trips of about 12 days each on my bike. I have a build motor in my 2013 with larger cylinders, 110 to 117. Much higher compression, head work and so on. Bike has no problem doing 600 mile days. My 19 will make more power with less compression. So coast to coast should be no issue.
Here is a link to the suburban kits. They sell the pistons separate if you want to build your own kit.
https://suburbanharley.com/Performance-Kits-Milwaukee-Eight