If you want to do this on the cheap your going down the wrong path looking to convert a early 235 or a 216 to full pressure oiling. All the parts cost a good chunk of money and the machine shop bill will be enough to open your eyes to.
There are a good number of used engines around to be had, usually your going to get what you pay for.
From the sound of things your expectations are higher than can be expected from these old engines. It may be time for you to get a crate motor and move on.
I have a number of these old ones running and enjoy driving them, I do remind myself to sit back and enjoy, if I'm in a hurry then I'll get in my Silverado and run 80.
Don
