can a four link front run at freeway speeds
Lots of variables with that question, is there a panhard and is there a steering box? If its a typical triangulated 4link with no panhard and a steering box then NO dont run it. Unless you like lots of bump steer. You know, hit a bump and the steering wheel turns a quarter or more of a revolution in your hand.
If its full hydro then you can except that if the motor dies you have no steering at all.
The safest way is to run a 3link with panhard and keep your steering box and hysteer.
Or if you're really good with geometry you can do a triangulated 4link with a steering box under you seat and an idler arm on the axle. But thats a whole other discussion.
If you want more info why dont you buy the July/August issue of 4WD Toyota Owner Mag and read all seven pages of suspension tech I wrote, starting on page 38. It may just answer you questions.