Welcome to ModelEngineMaker !If you have problems registering or logging in, please use the contact menu option to request assistance.
Common practice on the original engines of the period and thats whats being replicated, some also had extended screws so you could get at the heads if the skirt was long. Plus the pin won't wear the piston as the only movement is between pin and little end.Also can't see how you could get an e-clip on the end of a pin, you may be able to use circlips on larger engines fitting into grooves in the piston or more common on our small engines is a bronze or teflon button on the pin ends to stop it rubbing the cylinder
Grooves & hole are in the piston not the cylinder.