Exhaust cover is the normal candidate for the elbow on that engine. Someone should have a photo of the OEM location to post. Run the hose up and over the top of the cylinders before dropping down and hooking it up to your pan fitting.
Well I havent seen any factory water indicator on this block design. By looking at the parts breakdowns it looks like they started putting them on from the factory in 1977. Its a different block design. On the 77 model, its at the bottom of the exhaust cover. I seen where someone put it in the thermostat cover but it was on a 6 hp. I figure it was a good place because if you messed up it would be a cheaper fix.
Nobody said it was on there in your model year! Yes.....am just having a bit of fun with you.
The reason for the exhaust cover is that you get full water flow there. Doesnt have to be at the bottom...just away from a casting is good enough.