low oil pressure

I just small blocked my s10 and the motor I used is out of a firebird and has been sitting for a while but it ran good and did not smoke or knock I don't remember my oil pressure but it should not have been low or I would not have used the engine but now at idle hot I have 10 psi and at 3000rpm I have 35 I am used to like 20 at idle and 50-60 above idle, please help any suggestions, I am running 10w30 like it calls for and it being summer here high temps are 85-95 and 70 at night I just don't want to ruin an engine but don't want to have to pull it back out again I am kicking myself in the but for not putting a high volume pump in while the motor was on the enginge stand waiting but I did not so here I am I am planning a engine flush and an oil change with a new acdelco filter and 10w40 instead of the 10w30 and acdelco ac454 oil filter now

could be the pressure sender and pressure guage are now a mis-match. check the oil pressure with a mechanical guage to see if it's truely low.

it was low but i also hooked up a tach and she was idle at 450 rpm i had to do some mods but it is now at 625 and i got 10-15 at idle and 25-35 at 3000 rpm