Doug,
You might ask this question to the old GMC trucks forum, oldgmctrucks.com There are a lot of helpful members there that have a wealth of information about these GMC engines. I think the overflo tube goes on the number 4 rocker arm support. The oil from that tube flows down almost on top of the distributor gear. I dont think it should be crimped. Your oil pressure is probably ok for a engine with some wear.