You'll likely be fine with the #105 mainjets because of modern fuels, much more than because of the pipes. The modern Midgrade gas burns slow enough to use #105 jets with most of the cams and pipes Honda made. I'd suggest starting with that gas, and after 100 miles if the plugs are dark, switch to Regular instead. If they are white, switch up to Premium. It's rare for the post-K1 bikes to need any more jetting than that: while they often get "jetted up" because richer mix usually adds a small amount more torque at lower RPM, it usually ends up just fouling sparkplugs in very few miles. For dragracing, that's fine: we used to change plugs for about every 2nd run with the K0 hotrod bikes jetted 'way up' to #125 or even #130 mains, but they couldn't ride one day in commuter traffic like that without fouling a set of plugs. The early sandcast carbs came with #120, which usually got jetted down to #115 and then #110 when the customers griped about the plug fouling. The earliest K1 bikes with the 657A carbs came with #115 mains (mine had those) that got 100 miles to a set of plugs, so those usually got trimmed back to #110, quickly, and the needles dropped a notch or the emulsifier holes drilled out to larger sizes (or both, if not a spirited rider). Then, as if Honda was listening to their mechanics (they usually didn't) the 657B carbs suddenly appeared in 3/72 and later bikes with the #105 mainjets, which stayed until the PD carbs came along.
