help with bastardized open cooling conversion

Here is my problem; I've bought a 90 laredo(4.0 renix, aw4, np231) about a year ago. It has a metal radiator with pressure cap. The pressure bottle is still plumbed in and still on the firewall. The heater valve is the closed system type. The thermostat cover/inlet is a 92+(guessing because it has the plug for the electric fan in it) However, the radiator has the oem sensor/fan switch threaded into it in what I assume the stock location. I was wondering if there were models or years where the radiators came with this threaded into an open system radiator? There is no overflow tube the line for that is capped at the filler neck. Can the pressure bottle be used as an overflow? And my main question, What is necessary to complete this conversion? I'm not allowed attachments or I would post pictures for clarity. Any help would be greatly appreciated. I have another issue with the xj but that is for another post.

Plumb the heater core directly with no valve. Overflow tanks are cheap. Get one and hook that up to the capped tube with a small hose. There are a lot of threads showing how to do that. You already have the radiator. That's the main part.

Read the threads referenced at the bottom of the page here.

I'll check them out, thanks. Just curious, it sure didn't look right to me.