I know, i miss that big old stock thing. But the power steering pump had to go there. It was off the shelf and sorta fit and does a job. It'll have to do for now.
Probably the Late F engine, or 1.5 F.
Especially if you have the 4 speed.
I've had my 12/'74 FJ55 for 36 years. I used to drive it at 60, occasionally 65 mph. I really liked the 55mph speed limit.
A stockish 55 in good shape should be able to do that.
Have you given your engine a thourough...