Oil Viscosity,Filter, and Pressure

[lerch]

OK,New to the group here fellas,,..so be nice to me!
Just finished off my 57 Chevy Wagon with a new paint and interiour.It has a 350 out of a 1975 c-10 truck and freshly rebuilt.About 3000 miles on it.i bought it that way from the first owner.Just a simple question on oil viscosity and what filter.
i can't seem to find out anywhere to give me the specs on what is recomended oil viscosity.Also,the oil pressure i have read should anywhere from 20-40 normaly,right? i bought a Hastings Oil filter and back 25 yrs ago they used to use a cotton fiber media.not so anymore?Are they still good,or better? I hear Wix is a favorite.
As far as my driving habits for it...it will be as many Classics,just a Saturday night Cruiser or Sunday drive.And i live in Texas ,so the winters are mild and the summers,well hot as hell. Also it is kind of low geared in the rear,but not sure what it is.So,hiway,it revs pretty high.Hope this is helpful in determining the proper oil visc.
Thanks for any replies,
Lerch