bought a sbc from a 90 truck to rebuild and convert to carb.... with the factory 9.5 comp ratio is this a  disaster or can i exchange heads and the thing actually run good on pump gas... there are alot of options just looking for some  advice... thanks  

How is 9.5:1 a disaster on pump fuel?  

i'd like to know that myself... several people clain that with out running the knock sensor and the tbi it will be poor on low octane fuel...my beleif is build it and run it  

A TBI unit is not much more efficient than a carburetor, so that surely shouldn't make much difference...

The knock sensor has absolutely nothing to do with the engine's tendency to detonate/preignite, it may just help save an engine if the detonation is especially bad.

9.5:1 is pushing low-octane pump a little but it's surely not impossible. This is a good read on the subject
"The Power Squeeze" - by David Vizard  

The 350 out of the '90 truck should be 9:1, not 9.5:1. My '92 Chevy Silverado has 9:1 compression from the factory and runs fine on 87 octane.

Even with 9.5:1 compression, if the ignition system whatever your putting this motor in is working properly and the timing set correctly, you shouldn't have detonation problems on 87 octane. At worst, you'll have to run 89.