I have an '81 g-series van w/a small block. Notice my oil pressure gauge spike a bit upon acceleration and i'm getting a ton of exhaust. Mechanically inclined but inexperienced. Where should I start?

 

What does the exhaust look like? The oil pressure will rise with engine rpm

 

It could be because its dropping too low at idle, which will make for a longer jump in pressure during higher revs.
Are you using high mileage oil? Try a good one like valvoline max life......you may see an increase in pressure at lower rpm's.
Also, the guage could be getting old, and not showing a smooth arc, but jumping with the voltage......(sending unit could also cause this)