Christopher,
To answer your question about oil pressure:
You either have a lower-pressure 235 or a higher pressure 235.
The lower pressure 235 has an oil gauge with a range of about 0-30 and the higher pressure 235 has an oil gauge of approximately 0-60.
15 psi or 30 psi in either system while driving is a good pressure. At idle, it is common for an older engine to have lower psi (in both lower-pressure and higher-pressure 235s). As the engine gets older (bearing clearances get wider, etc), the pressure at idle gets lower.
I had a higher pressure 235 that had good pressure when running, but it had very low pressure when idling (around 5 psi). I took out the engine and replaced it when it idled with a 0 psi reading. No sense gambling on when the engine would seize or otherwise break down.
