Thanks guys. There is only one variation example I am missing (that I know of for sure), the oscillating piston with reverser lever
without the water pump. That would give me 8, which is a nice round number too LOL! There was one on eBay for a bit but I just couldn't buy it - it was missing most, if not nearly all, its nickel plating (being polished to base metal). I'd take a pitted, rusted, dinged up engine over one that has been "restored" and its nickel purposely removed. I have standards ha!
I should also shout out to
@txlabman for the Empire sign you see in the background. That was a gift to me when my brother stopped by his place a few months ago. I LOVE that sign :-)