Yes, I have a VERY similar problem right now. Mine busted or something within the last couple of days and was leaking a bit of oil every now and then. Just keep her oiled up until you fix it. It's $14.99 at O'Reilly Auto Parts.
My pressure would read 60 sometimes, then 30, then 0 sometimes too. That's what tipped it off. Many old Chevy's have this problem.
http://my85silverado.tripod.com/