Randy, Perkins used only one cam bushing. The front cam journal rides on a bushing. the back three journals ride directly on the cast iron block. Some very early 4.236 used no bushing.
When removing original liners I've noticed it takes over 30 ton to get them moving. The original liners are press fit, finish bored and honed in place("en situ" as the service manual states). If it has been rebuilt, it likely has slip fit service liners which will come out much easier.
In the O/H kits, Service liners(slip fit, pre finished...) are supplied. It's a common mistake is to use them. There are three different designs of liners Perkins used throughout the production life of the 4.236. Of those three designs, there are 2-5 options of each(over sized, finished, unfinished, chrome...).
From the picture of the piston roast, it looks like you have the 1st or 2nd design. If you have 1st design, update to 2nd design p#31358394 for the finished liner, 31358393 for unfinished. Double check the p#'s, sometimes my memory fails me.
Back to the common mistake. After you press out the liners, check the liner parent bores in the block. After many years of thermal cycling, they can grow and be out of round. The service liner calls for .001" clearance to .001" interference("transition fit"). If you are handing it over to your local machine shop, make damn sure your he checks it. I have seen more than one guy screwed by his local machine shop when he failed to check the parent bore and address the bores condition. Failure of this will score pistons within hours repeatedly until rectified. Every block I ever checked the parent bores, was borderline bad. I pressed in the unfinished liner which is a press fit instead of a slip fit. Then had the unfinished liner bored and honed to size. That way I slept well at night knowing that hole was round and true.
If you want, post a pic of a liner after it is pressed out and I'll identify it.
