Thanks Charlie - I know you have a lots of 43s in your collection (I love that video of them on your YouTube channel).
I have a 90 "replacement" coming via a eBay win that no one else bid on (mine is not in so good condition but it was horribly bad/dead before I started working on it). I also have a B-43/#43 Water Pumper & Reversing Lever with oscillating cylinder that I negotiated with SlowJoey outside of eBay (I am pretty sure is pictured in Donald Stilson's Empire book at the bottom of page 43).
I think I am now down to looking for these B/No. 43's: one with straps, one with just the water pump (no reverse lever?), and I guess the one with the pressure gauge. I think these are all oscillating cylinder engines and the gauge one is a bit of a unicorn I think.