I don't know exactly which engine you are talking about, but based on a few assorted engines i've rebuilt, the tiller "lump" will probably be integral to the bottom of the engine, and so the best thing is to find / make a blanking plate for it. I have a Suzi 25 (early 90s vintage) and a late 60s / early 70s Johnson 25 both of which have that arrangement.
As for the connection to the link rod, there are two possibilities:
1)have a look in from the front under the cowling. you may find a cast lump with two holes facing forwards. That is where you bolt the other casting that forms the "tiller " and will poke out slighty ahead of the cowl. I haven't checked any microfiches, but I'll guess if it has that arrangement, the same tiller casting was probably used on numerous different engines of the time. You'll need to find or fabricate one to bolt on.
2)There may also be a slotted hole in the middle of the "carrying handle". Back then wire steering was more common, and so there were attatchements that bolted on there to which you attatched the wires. A bit like this: http://www.old-omc.de/e_1970/seite_12.jpg
This conveniently shows what you could do in that situation - but bolt an angle to it which you can then bolt the link arm to the horizontal plate.