The bushes are what's called an interference fit which means they are indeed very very tight but generally you fit them with some oil, a bolt and plenty of thick, wide washers.

Put the yoke in a vice and thread the bolt (with washers) through the bush. Offer it up to the yoke and use a nut with plenty of washers underneath so now the bolt goes through both bush and yolk.

Hold the bush straight and start tightening the nut, gradually the bush will just slip into place.

If the bush doesn't want to sit properly at the start use a grinding wheel to dress the outer edge of it to give it a slight taper and then use a half round file on the inner edge of the yoke top to make a similar profile. You'll find it will sit slightly better then and should give you a starting point.

Of course, make sure you have the right size to begin with by measuring both bush and yoke. They should be the same, give or take a few thou, so if the difference is markedly different then you may have a dud pattern part!

Cheers
Rudi