Thanks for the responses.
I am connecting it to a '78 Evinrude 85hp, with tilt/trim.
I actually found a clevis in the garage last night after I wrote the post. I'm concerned that it won't fit for two reasons. First, the end of the steering cable is threaded (1/2" NF threads, I think). The hole in the cable may be too far starboard to make a good connection to the clevis (you can see this in the picture). Second, and I haven't confirmed this, I don't think that the bolts that came with the clevis kit will fit into the mounting hole in the steering linkage on the motor. I'll know more tonight when I try this (if it ever stops raining long enough).
I'm also concerned that the cable may not have enough play, or be at the wrong angle with respect to the motor tilting. The control arm that I took off had a ball joint on the motor end to allow for that movement, but it came out of a tilt tube steering system.