As another 3D printer enthusiast, I will chime in with my 2 cents. Nice design you have which can print as shown with no overhangs. Rather than tinkering with slicer settings to deal with shrinkage in holes, I have just taken to pressing them out by 0.1mm to 0.2mm in the original design where fit is critical.
Another strong filament option I use on my gear is "high-temperature PLA". I specifically have been using Veracity ProPLA from Filastruder. Prints like PLA but at a higher temp 230C / 60C, and tolerates exposure to sun and hot car as well as PETG.? Personally, I would avoid 100% infill. You get good strength with 50% infill or less and 4 or 5 layers on the base and walls. Dimensional consistency I have found to be better with partial infill.
--
Edward
Edward Plumer