There are lots of scoping possibilites listed in the FAQs sticky, how low it's mounted mostly depends on the scope itself, how big the ocular bell/power ring(if variable power) are and how far forward it's mounted, rifles and shotguns share the same bases and hammer arrangement, so that makes no difference. The Weaver #82 and Ultra bases can be used to mount a small fixed power scope in low rings so the scope is ahead of the hammer, that's shown in the FAQs also, a larger scope will require medium or high rings to clear the hammer unless hammer mods are made, low profile hammer mods are also covered in detail in the FAQs.
Tim