Please pay no mind to anything the phyco motor guy says. He is dispensing crap all over the place.
Shovelutions are not that uncommon. Good build actually. Axtell can make a cylinder to fit almost any combination of base pattern to almost any head.
From the pics it look like the OP has Axtell cast iron cylinders with short shovel style cylinder studs. Might not be an actual shovelution.
Back to the oil pump. The cam chests on later shovels and early evo engines is exactly the same.
The OP says he can move the gear on the pinion shaft about a 1/4". The snap ring idea is crap.
The oil pump gear on the pinion shaft will move a bunch, that is normal. Not necessarily .250", but it is supposed to move.
Does your engine look sort of like this: