Original prop for 74 v step 165 hp 6 cyl?

[Dodgerrr]

Hi Guys. I finally had the chance of taking out the old boat only to hit a rock and damage the prop.
Specs:
Prop #18-78122-21
Engine 165 Merc inboard 6 cyl.
Max rpm 4100.
Max speed 38 mph, I think.

Now when I went to install the prop I noticed that the splines did not protrude past the prop at all for the brass locking collar to engage with. I guess last the few years, the only thing locking the nut from spinning off was nothing at all? Some one said the tapered spacer may be too thick which results in an inability to lock the nut properly.

I think the guy I bought the boat from did some swapping before I bought it. BTW, I know nothing.

Question? Does any one know or have the original prop or information that may have come with this boat when new? Is this the correct prop. I think max RPM should be around 4400.

This also takes for ever to get up on plane. It also steers terrible always pulling hard to the left. Yes and there is some klunking in the shafts when I steer sharp and hard at hi speeds.
I swear I need 40 acres to get this thing turned around. It is easier to stop, slowly turn and then gun it back up to speed.

Your thoughts are appreciated.
Dodgerrr.